Reland r130462: Implement FeatureProvider for ExtensionAPI."

chrome/common/extensions/api/extension_api.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/common/extensions/api/extension_api.h"
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
 #include "base/json/json_reader.h"
+#include "base/json/json_writer.h"
+#include "base/lazy_instance.h"
 #include "base/logging.h"
+#include "base/string_number_conversions.h"
 #include "base/string_split.h"
 #include "base/string_util.h"
 #include "base/values.h"
 #include "chrome/common/extensions/api/generated_schemas.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/extension_permission_set.h"
+#include "chrome/common/extensions/simple_feature_provider.h"
+#include "content/public/browser/browser_thread.h"
 #include "googleurl/src/gurl.h"
 #include "grit/common_resources.h"
 #include "ui/base/resource/resource_bundle.h"
 
 using base::DictionaryValue;
 using base::ListValue;
 using base::Value;
+using content::BrowserThread;
 
 namespace extensions {
 
 using api::GeneratedSchemas;
 
 namespace {
 
+const char* kChildKinds[] = {
+  "functions",
+  "events"
+};
+
 // Returns whether the list at |name_space_node|.|child_kind| contains any
 // children with an { "unprivileged": true } property.
 bool HasUnprivilegedChild(const DictionaryValue* name_space_node,
                           const std::string& child_kind) {
   ListValue* child_list = NULL;
   name_space_node->GetList(child_kind, &child_list);
   if (!child_list)
     return false;
 
   for (size_t i = 0; i < child_list->GetSize(); ++i) {
@@ skipping 17 matching lines @@
       base::JSONReader::ReadAndReturnError(
           schema.as_string(),
           false, // allow trailing commas
           NULL,  // error code
           &error_message));
   CHECK(result.get()) << error_message;
   CHECK(result->IsType(Value::TYPE_LIST));
   return scoped_ptr<ListValue>(static_cast<ListValue*>(result.release()));
 }
 
+DictionaryValue* FindListItem(const ListValue* list,
+                              const std::string& property_name,
+                              const std::string& property_value) {
+  for (size_t i = 0; i < list->GetSize(); ++i) {
+    DictionaryValue* item = NULL;
+    CHECK(list->GetDictionary(i, &item))
+        << property_value << "/" << property_name;
+    std::string value;
+    if (item->GetString(property_name, &value) && value == property_value)
+      return item;
+  }
+
+  return NULL;
+}
+
+const DictionaryValue* GetSchemaChild(const DictionaryValue* schema_node,
+                                      const std::string& child_name) {
+  DictionaryValue* child_node = NULL;
+  for (size_t i = 0; i < arraysize(kChildKinds); ++i) {
+    ListValue* list_node = NULL;
+    if (!schema_node->GetList(kChildKinds[i], &list_node))
+      continue;
+    child_node = FindListItem(list_node, "name", child_name);
+    if (child_node)
+      return child_node;
+  }
+
+  return NULL;
+}
+
+struct Static {
+  Static()
+      : api(ExtensionAPI::CreateWithDefaultConfiguration()) {
+  }
+  scoped_ptr<ExtensionAPI> api;
+};
+
+base::LazyInstance<Static> g_lazy_instance = LAZY_INSTANCE_INITIALIZER;
+
 }  // namespace
 
 // static
-ExtensionAPI* ExtensionAPI::GetInstance() {
-  return Singleton<ExtensionAPI>::get();
+ExtensionAPI* ExtensionAPI::GetSharedInstance() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  return g_lazy_instance.Get().api.get();
+}
+
+// static
+ExtensionAPI* ExtensionAPI::CreateWithDefaultConfiguration() {
+  ExtensionAPI* api = new ExtensionAPI();
+  api->InitDefaultConfiguration();
+  return api;
+}
+
+// static
+void ExtensionAPI::SplitDependencyName(const std::string& full_name,
+                                       std::string* feature_type,
+                                       std::string* feature_name) {
+  size_t colon_index = full_name.find(':');
+  if (colon_index == std::string::npos) {
+    // TODO(aa): Remove this code when all API descriptions have been updated.
+    *feature_type = "api";
+    *feature_name = full_name;
+    return;
+  }
+
+  *feature_type = full_name.substr(0, colon_index);
+  *feature_name = full_name.substr(colon_index + 1);
 }
 
 void ExtensionAPI::LoadSchema(const base::StringPiece& schema) {
   scoped_ptr<ListValue> schema_list(LoadSchemaList(schema));
   std::string schema_namespace;
 
   while (!schema_list->empty()) {
     const DictionaryValue* schema = NULL;
     {
       Value* value = NULL;
@@ skipping 23 matching lines @@
     if (schema->GetList("matches", &matches)) {
       URLPatternSet pattern_set;
       for (size_t i = 0; i < matches->GetSize(); ++i) {
         std::string pattern;
         CHECK(matches->GetString(i, &pattern));
         pattern_set.AddPattern(
             URLPattern(UserScript::kValidUserScriptSchemes, pattern));
       }
       url_matching_apis_[schema_namespace] = pattern_set;
     }
+
+    // Populate feature maps.
+    // TODO(aa): Consider not storing features that can never run on the current
+    // machine (e.g., because of platform restrictions).
+    bool uses_feature_system = false;
+    schema->GetBoolean("uses_feature_system", &uses_feature_system);
+    if (!uses_feature_system)
+      continue;
+
+    Feature* feature = new Feature();
+    feature->set_name(schema_namespace);
+    feature->Parse(schema);
+
+    FeatureMap* schema_features = new FeatureMap();
+    CHECK(features_.insert(
+        std::make_pair(schema_namespace,
+                       make_linked_ptr(schema_features))).second);
+    CHECK(schema_features->insert(
+        std::make_pair("", make_linked_ptr(feature))).second);
+
+    for (size_t i = 0; i < arraysize(kChildKinds); ++i) {
+      ListValue* child_list = NULL;
+      schema->GetList(kChildKinds[i], &child_list);
+      if (!child_list)
+        continue;
+
+      for (size_t j = 0; j < child_list->GetSize(); ++j) {
+        DictionaryValue* child = NULL;
+        CHECK(child_list->GetDictionary(j, &child));
+
+        scoped_ptr<Feature> child_feature(new Feature(*feature));
+        child_feature->Parse(child);
+        if (child_feature->Equals(*feature))
+          continue;  // no need to store no-op features
+
+        std::string child_name;
+        CHECK(child->GetString("name", &child_name));
+        child_feature->set_name(schema_namespace + "." + child_name);
+        CHECK(schema_features->insert(
+            std::make_pair(child_name,
+                           make_linked_ptr(child_feature.release()))).second);
+      }
+    }
   }
 }
 
 ExtensionAPI::ExtensionAPI() {
+  RegisterDependencyProvider("api", this);
+
+  // TODO(aa): Can remove this when all JSON files are converted.
+  RegisterDependencyProvider("", this);
+}
+
+ExtensionAPI::~ExtensionAPI() {
+}
+
+void ExtensionAPI::InitDefaultConfiguration() {

[Matt Perry, 2012/04/04 18:38:47]

This method is called when you create a new ExtensionAPI instance, and it causes
all the JSON files to be read into memory. It looks like that's about 700K. Even
adding that much is a waste when we could just special-case the webRequest API
to avoid instantiating an ExtensionAPI on the IO thread.

[Aaron Boodman, 2012/04/04 18:41:27]

It doesn't actually do any reading. ReadFromResource is named badly. All it's
returning is a StringPiece. The data is actually read into memory later, in
LoadSchema().

+  RegisterDependencyProvider(
+      "manifest", SimpleFeatureProvider::GetManifestFeatures());
+  RegisterDependencyProvider(
+      "permission", SimpleFeatureProvider::GetPermissionFeatures());
+
   // Schemas to be loaded from resources.
-  unloaded_schemas_["app"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_APP);
-  unloaded_schemas_["bookmarks"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_BOOKMARKS);
-  unloaded_schemas_["browserAction"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_BROWSERACTION);
-  unloaded_schemas_["browsingData"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_BROWSINGDATA);
-  unloaded_schemas_["chromeAuthPrivate"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_CHROMEAUTHPRIVATE);
-  unloaded_schemas_["chromeosInfoPrivate"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_CHROMEOSINFOPRIVATE);
-  unloaded_schemas_["contentSettings"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_CONTENTSETTINGS);
-  unloaded_schemas_["contextMenus"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_CONTEXTMENUS);
-  unloaded_schemas_["cookies"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_COOKIES);
-  unloaded_schemas_["debugger"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_DEBUGGER);
-  unloaded_schemas_["devtools"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_DEVTOOLS);
-  unloaded_schemas_["experimental.accessibility"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_ACCESSIBILITY);
-  unloaded_schemas_["experimental.alarms"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_ALARMS);
-  unloaded_schemas_["experimental.app"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_APP);
-  unloaded_schemas_["experimental.bookmarkManager"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_BOOKMARKMANAGER);
-  unloaded_schemas_["experimental.declarative"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_DECLARATIVE);
-  unloaded_schemas_["experimental.downloads"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_DOWNLOADS);
-  unloaded_schemas_["experimental.extension"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_EXTENSION);
-  unloaded_schemas_["experimental.fontSettings"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_FONTSSETTINGS);
-  unloaded_schemas_["experimental.identity"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_IDENTITY);
-  unloaded_schemas_["experimental.infobars"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_INFOBARS);
-  unloaded_schemas_["experimental.input.ui"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_INPUT_UI);
-  unloaded_schemas_["experimental.input.virtualKeyboard"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_INPUT_VIRTUALKEYBOARD);
-  unloaded_schemas_["experimental.keybinding"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_KEYBINDING);
-  unloaded_schemas_["experimental.managedMode"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_MANAGEDMODE);
-  unloaded_schemas_["experimental.offscreenTabs"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_OFFSCREENTABS);
-  unloaded_schemas_["experimental.processes"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_PROCESSES);
-  unloaded_schemas_["experimental.rlz"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_RLZ);
-  unloaded_schemas_["experimental.serial"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_SERIAL);
-  unloaded_schemas_["experimental.socket"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_SOCKET);
-  unloaded_schemas_["experimental.speechInput"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_SPEECHINPUT);
-  unloaded_schemas_["experimental.webRequest"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXPERIMENTAL_WEBREQUEST);
-  unloaded_schemas_["extension"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_EXTENSION);
-  unloaded_schemas_["fileBrowserHandler"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_FILEBROWSERHANDLER);
-  unloaded_schemas_["fileBrowserPrivate"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_FILEBROWSERPRIVATE);
-  unloaded_schemas_["history"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_HISTORY);
-  unloaded_schemas_["i18n"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_I18N);
-  unloaded_schemas_["idle"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_IDLE);
-  unloaded_schemas_["input.ime"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_INPUT_IME);
-  unloaded_schemas_["inputMethodPrivate"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_INPUTMETHODPRIVATE);
-  unloaded_schemas_["management"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_MANAGEMENT);
-  unloaded_schemas_["mediaPlayerPrivate"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_MEDIAPLAYERPRIVATE);
-  unloaded_schemas_["metricsPrivate"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_METRICSPRIVATE);
-  unloaded_schemas_["offersPrivate"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_OFFERSPRIVATE);
-  unloaded_schemas_["omnibox"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_OMNIBOX);
-  unloaded_schemas_["pageAction"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_PAGEACTION);
-  unloaded_schemas_["pageActions"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_PAGEACTIONS);
-  unloaded_schemas_["pageCapture"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_PAGECAPTURE);
-  unloaded_schemas_["permissions"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_PERMISSIONS);
-  unloaded_schemas_["privacy"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_PRIVACY);
-  unloaded_schemas_["proxy"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_PROXY);
-  unloaded_schemas_["storage"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_STORAGE);
-  unloaded_schemas_["systemPrivate"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_SYSTEMPRIVATE);
-  unloaded_schemas_["tabs"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_TABS);
-  unloaded_schemas_["terminalPrivate"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_TERMINALPRIVATE);
-  unloaded_schemas_["test"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_TEST);
-  unloaded_schemas_["topSites"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_TOPSITES);
-  unloaded_schemas_["ttsEngine"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_TTSENGINE);
-  unloaded_schemas_["tts"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_TTS);
-  unloaded_schemas_["types"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_TYPES);
-  unloaded_schemas_["webNavigation"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_WEBNAVIGATION);
-  unloaded_schemas_["webRequest"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_WEBREQUEST);
-  unloaded_schemas_["webSocketProxyPrivate"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_WEBSOCKETPROXYPRIVATE);
-  unloaded_schemas_["webstore"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_WEBSTORE);
-  unloaded_schemas_["webstorePrivate"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_WEBSTOREPRIVATE);
-  unloaded_schemas_["windows"] = ReadFromResource(
-      IDR_EXTENSION_API_JSON_WINDOWS);
+  CHECK(unloaded_schemas_.empty());
+  RegisterSchema("app", ReadFromResource(
+      IDR_EXTENSION_API_JSON_APP));
+  RegisterSchema("bookmarks", ReadFromResource(
+      IDR_EXTENSION_API_JSON_BOOKMARKS));
+  RegisterSchema("browserAction", ReadFromResource(
+      IDR_EXTENSION_API_JSON_BROWSERACTION));
+  RegisterSchema("browsingData", ReadFromResource(
+      IDR_EXTENSION_API_JSON_BROWSINGDATA));
+  RegisterSchema("chromeAuthPrivate", ReadFromResource(
+      IDR_EXTENSION_API_JSON_CHROMEAUTHPRIVATE));
+  RegisterSchema("chromeosInfoPrivate", ReadFromResource(
+      IDR_EXTENSION_API_JSON_CHROMEOSINFOPRIVATE));
+  RegisterSchema("contentSettings", ReadFromResource(
+      IDR_EXTENSION_API_JSON_CONTENTSETTINGS));
+  RegisterSchema("contextMenus", ReadFromResource(
+      IDR_EXTENSION_API_JSON_CONTEXTMENUS));
+  RegisterSchema("cookies", ReadFromResource(
+      IDR_EXTENSION_API_JSON_COOKIES));
+  RegisterSchema("debugger", ReadFromResource(
+      IDR_EXTENSION_API_JSON_DEBUGGER));
+  RegisterSchema("devtools", ReadFromResource(
+      IDR_EXTENSION_API_JSON_DEVTOOLS));
+  RegisterSchema("experimental.accessibility", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_ACCESSIBILITY));
+  RegisterSchema("experimental.alarms", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_ALARMS));
+  RegisterSchema("experimental.app", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_APP));
+  RegisterSchema("experimental.bookmarkManager", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_BOOKMARKMANAGER));
+  RegisterSchema("experimental.declarative", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_DECLARATIVE));
+  RegisterSchema("experimental.downloads", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_DOWNLOADS));
+  RegisterSchema("experimental.extension", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_EXTENSION));
+  RegisterSchema("experimental.fontSettings", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_FONTSSETTINGS));
+  RegisterSchema("experimental.identity", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_IDENTITY));
+  RegisterSchema("experimental.infobars", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_INFOBARS));
+  RegisterSchema("experimental.input.ui", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_INPUT_UI));
+  RegisterSchema("experimental.input.virtualKeyboard", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_INPUT_VIRTUALKEYBOARD));
+  RegisterSchema("experimental.keybinding", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_KEYBINDING));
+  RegisterSchema("experimental.managedMode", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_MANAGEDMODE));
+  RegisterSchema("experimental.offscreenTabs", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_OFFSCREENTABS));
+  RegisterSchema("experimental.processes", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_PROCESSES));
+  RegisterSchema("experimental.rlz", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_RLZ));
+  RegisterSchema("experimental.serial", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_SERIAL));
+  RegisterSchema("experimental.socket", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_SOCKET));
+  RegisterSchema("experimental.speechInput", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_SPEECHINPUT));
+  RegisterSchema("experimental.webRequest", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXPERIMENTAL_WEBREQUEST));
+  RegisterSchema("extension", ReadFromResource(
+      IDR_EXTENSION_API_JSON_EXTENSION));
+  RegisterSchema("fileBrowserHandler", ReadFromResource(
+      IDR_EXTENSION_API_JSON_FILEBROWSERHANDLER));
+  RegisterSchema("fileBrowserPrivate", ReadFromResource(
+      IDR_EXTENSION_API_JSON_FILEBROWSERPRIVATE));
+  RegisterSchema("history", ReadFromResource(
+      IDR_EXTENSION_API_JSON_HISTORY));
+  RegisterSchema("i18n", ReadFromResource(
+      IDR_EXTENSION_API_JSON_I18N));
+  RegisterSchema("idle", ReadFromResource(
+      IDR_EXTENSION_API_JSON_IDLE));
+  RegisterSchema("input.ime", ReadFromResource(
+      IDR_EXTENSION_API_JSON_INPUT_IME));
+  RegisterSchema("inputMethodPrivate", ReadFromResource(
+      IDR_EXTENSION_API_JSON_INPUTMETHODPRIVATE));
+  RegisterSchema("management", ReadFromResource(
+      IDR_EXTENSION_API_JSON_MANAGEMENT));
+  RegisterSchema("mediaPlayerPrivate", ReadFromResource(
+      IDR_EXTENSION_API_JSON_MEDIAPLAYERPRIVATE));
+  RegisterSchema("metricsPrivate", ReadFromResource(
+      IDR_EXTENSION_API_JSON_METRICSPRIVATE));
+  RegisterSchema("offersPrivate", ReadFromResource(
+      IDR_EXTENSION_API_JSON_OFFERSPRIVATE));
+  RegisterSchema("omnibox", ReadFromResource(
+      IDR_EXTENSION_API_JSON_OMNIBOX));
+  RegisterSchema("pageAction", ReadFromResource(
+      IDR_EXTENSION_API_JSON_PAGEACTION));
+  RegisterSchema("pageActions", ReadFromResource(
+      IDR_EXTENSION_API_JSON_PAGEACTIONS));
+  RegisterSchema("pageCapture", ReadFromResource(
+      IDR_EXTENSION_API_JSON_PAGECAPTURE));
+  RegisterSchema("permissions", ReadFromResource(
+      IDR_EXTENSION_API_JSON_PERMISSIONS));
+  RegisterSchema("privacy", ReadFromResource(
+      IDR_EXTENSION_API_JSON_PRIVACY));
+  RegisterSchema("proxy", ReadFromResource(
+      IDR_EXTENSION_API_JSON_PROXY));
+  RegisterSchema("storage", ReadFromResource(
+      IDR_EXTENSION_API_JSON_STORAGE));
+  RegisterSchema("systemPrivate", ReadFromResource(
+      IDR_EXTENSION_API_JSON_SYSTEMPRIVATE));
+  RegisterSchema("tabs", ReadFromResource(
+      IDR_EXTENSION_API_JSON_TABS));
+  RegisterSchema("terminalPrivate", ReadFromResource(
+      IDR_EXTENSION_API_JSON_TERMINALPRIVATE));
+  RegisterSchema("test", ReadFromResource(
+      IDR_EXTENSION_API_JSON_TEST));
+  RegisterSchema("topSites", ReadFromResource(
+      IDR_EXTENSION_API_JSON_TOPSITES));
+  RegisterSchema("ttsEngine", ReadFromResource(
+      IDR_EXTENSION_API_JSON_TTSENGINE));
+  RegisterSchema("tts", ReadFromResource(
+      IDR_EXTENSION_API_JSON_TTS));
+  RegisterSchema("types", ReadFromResource(
+      IDR_EXTENSION_API_JSON_TYPES));
+  RegisterSchema("webNavigation", ReadFromResource(
+      IDR_EXTENSION_API_JSON_WEBNAVIGATION));
+  RegisterSchema("webRequest", ReadFromResource(
+      IDR_EXTENSION_API_JSON_WEBREQUEST));
+  RegisterSchema("webSocketProxyPrivate", ReadFromResource(
+      IDR_EXTENSION_API_JSON_WEBSOCKETPROXYPRIVATE));
+  RegisterSchema("webstore", ReadFromResource(
+      IDR_EXTENSION_API_JSON_WEBSTORE));
+  RegisterSchema("webstorePrivate", ReadFromResource(
+      IDR_EXTENSION_API_JSON_WEBSTOREPRIVATE));
+  RegisterSchema("windows", ReadFromResource(
+      IDR_EXTENSION_API_JSON_WINDOWS));
 
   // Schemas to be loaded via JSON generated from IDL files.
   GeneratedSchemas::Get(&unloaded_schemas_);
 }
 
-ExtensionAPI::~ExtensionAPI() {
+void ExtensionAPI::RegisterSchema(const std::string& name,
+                                  const base::StringPiece& source) {
+  unloaded_schemas_[name] = source;
+}
+
+void ExtensionAPI::RegisterDependencyProvider(const std::string& name,
+                                              FeatureProvider* provider) {
+  dependency_providers_[name] = provider;
+}
+
+bool ExtensionAPI::IsAvailable(const std::string& full_name,
+                               const Extension* extension,
+                               Feature::Context context) {
+  std::set<std::string> dependency_names;
+  dependency_names.insert(full_name);
+  ResolveDependencies(&dependency_names);
+
+  for (std::set<std::string>::iterator iter = dependency_names.begin();
+       iter != dependency_names.end(); ++iter) {
+    scoped_ptr<Feature> feature(GetFeatureDependency(full_name));
+    CHECK(feature.get()) << *iter;
+
+    Feature::Availability availability =
+        feature->IsAvailableToContext(extension, context);
+    if (availability != Feature::IS_AVAILABLE)
+      return false;
+  }
+
+  return true;
 }
 
 bool ExtensionAPI::IsPrivileged(const std::string& full_name) {
-  std::string api_name;
   std::string child_name;
-
-  {
-    std::vector<std::string> split;
-    base::SplitString(full_name, '.', &split);
-    std::reverse(split.begin(), split.end());
-    CHECK(!split.empty());  // |full_name| was empty or only whitespace.
-
-    api_name = split.back();
-    split.pop_back();
-    if (api_name == "experimental") {
-      CHECK(!split.empty());  // |full_name| was "experimental" alone.
-      api_name += "." + split.back();
-      split.pop_back();
+  std::string api_name = GetAPINameFromFullName(full_name, &child_name);
+
+  // First try to use the feature system.
+  scoped_ptr<Feature> feature(GetFeature(full_name));
+  if (feature.get()) {
+    // An API is 'privileged' if it or any of its dependencies can only be run
+    // in a blessed context.
+    std::set<std::string> resolved_dependencies;
+    resolved_dependencies.insert(full_name);
+    ResolveDependencies(&resolved_dependencies);
+    for (std::set<std::string>::iterator iter = resolved_dependencies.begin();
+         iter != resolved_dependencies.end(); ++iter) {
+      scoped_ptr<Feature> dependency(GetFeatureDependency(*iter));
+      for (std::set<Feature::Context>::iterator context =
+               dependency->contexts()->begin();
+           context != dependency->contexts()->end(); ++context) {
+        if (*context != Feature::BLESSED_EXTENSION_CONTEXT)
+          return false;
+      }
     }
-
-    // This only really works properly if split.size() == 1, however:
-    //  - if it's empty, it's ok to leave child_name empty; presumably there's
-    //    no functions or events with empty names.
-    //  - if it's > 1, we can just do our best.
-    if (split.size() > 0)
-      child_name = split[0];
+    return true;
   }
 
-  // GetSchema to ensure that it gets loaded before any checks.
-  const DictionaryValue* schema = GetSchema(api_name);
-
+  // If this API hasn't been converted yet, fall back to the old system.
   if (completely_unprivileged_apis_.count(api_name))
     return false;
 
-  if (partially_unprivileged_apis_.count(api_name)) {
-    return IsChildNamePrivileged(schema, "functions", child_name) &&
-           IsChildNamePrivileged(schema, "events", child_name);
-  }
+  const DictionaryValue* schema = GetSchema(api_name);
+  if (partially_unprivileged_apis_.count(api_name))
+    return IsChildNamePrivileged(schema, child_name);
 
   return true;
 }
 
-DictionaryValue* ExtensionAPI::FindListItem(
-    const ListValue* list,
-    const std::string& property_name,
-    const std::string& property_value) {
-  for (size_t i = 0; i < list->GetSize(); ++i) {
-    DictionaryValue* item = NULL;
-    CHECK(list->GetDictionary(i, &item))
-        << property_value << "/" << property_name;
-    std::string value;
-    if (item->GetString(property_name, &value) && value == property_value)
-      return item;
-  }
-
-  return NULL;
-}
-
 bool ExtensionAPI::IsChildNamePrivileged(const DictionaryValue* name_space_node,
-                                         const std::string& child_kind,
                                          const std::string& child_name) {
-  ListValue* child_list = NULL;
-  name_space_node->GetList(child_kind, &child_list);
-  if (!child_list)
-    return true;
-
   bool unprivileged = false;
-  DictionaryValue* child = FindListItem(child_list, "name", child_name);
+  const DictionaryValue* child = GetSchemaChild(name_space_node, child_name);
   if (!child || !child->GetBoolean("unprivileged", &unprivileged))
     return true;
 
   return !unprivileged;
 }
 
-const DictionaryValue* ExtensionAPI::GetSchema(const std::string& api_name) {
-  SchemaMap::const_iterator maybe_schema = schemas_.find(api_name);
-  if (maybe_schema != schemas_.end())
-    return maybe_schema->second.get();
-
-  // Might not have loaded yet; or might just not exist.
-  std::map<std::string, base::StringPiece>::iterator maybe_schema_resource =
-      unloaded_schemas_.find(api_name);
-  if (maybe_schema_resource == unloaded_schemas_.end())
-    return NULL;
-
-  LoadSchema(maybe_schema_resource->second);
-  maybe_schema = schemas_.find(api_name);
-  CHECK(schemas_.end() != maybe_schema);
-  return maybe_schema->second.get();
+const DictionaryValue* ExtensionAPI::GetSchema(const std::string& full_name) {
+  std::string child_name;
+  std::string api_name = GetAPINameFromFullName(full_name, &child_name);
+
+  const DictionaryValue* result = NULL;
+  SchemaMap::iterator maybe_schema = schemas_.find(api_name);
+  if (maybe_schema != schemas_.end()) {
+    result = maybe_schema->second.get();
+  } else {
+    // Might not have loaded yet; or might just not exist.
+    std::map<std::string, base::StringPiece>::iterator maybe_schema_resource =
+        unloaded_schemas_.find(api_name);
+    if (maybe_schema_resource == unloaded_schemas_.end())
+      return NULL;
+
+    LoadSchema(maybe_schema_resource->second);
+    maybe_schema = schemas_.find(api_name);
+    CHECK(schemas_.end() != maybe_schema);
+    result = maybe_schema->second.get();
+  }
+
+  if (!child_name.empty())
+    result = GetSchemaChild(result, child_name);
+
+  return result;
 }
 
 scoped_ptr<std::set<std::string> > ExtensionAPI::GetAPIsForContext(
     Feature::Context context, const Extension* extension, const GURL& url) {
   // We're forced to load all schemas now because we need to know the metadata
   // about every API -- and the metadata is stored in the schemas themselves.
   // This is a shame.
   // TODO(aa/kalman): store metadata in a separate file and don't load all
   // schemas.
   LoadAllSchemas();
 
-  scoped_ptr<std::set<std::string> > result(new std::set<std::string>());
+  std::set<std::string> temp_result;
 
+  // First handle all the APIs that have been converted to the feature system.
+  if (extension) {
+    for (APIFeatureMap::iterator iter = features_.begin();
+         iter != features_.end(); ++iter) {
+      if (IsAvailable(iter->first, extension, context))
+        temp_result.insert(iter->first);
+    }
+  }
+
+  // Second, fall back to the old way.
+  // TODO(aa): Remove this when all APIs have been converted.
   switch (context) {
     case Feature::UNSPECIFIED_CONTEXT:
       break;
 
     case Feature::BLESSED_EXTENSION_CONTEXT:
       // Availability is determined by the permissions of the extension.
       CHECK(extension);
-      GetAllowedAPIs(extension, result.get());
-      ResolveDependencies(result.get());
+      GetAllowedAPIs(extension, &temp_result);
+      ResolveDependencies(&temp_result);
       break;
 
     case Feature::UNBLESSED_EXTENSION_CONTEXT:
     case Feature::CONTENT_SCRIPT_CONTEXT:
       // Same as BLESSED_EXTENSION_CONTEXT, but only those APIs that are
       // unprivileged.
       CHECK(extension);
-      GetAllowedAPIs(extension, result.get());
+      GetAllowedAPIs(extension, &temp_result);
       // Resolving dependencies before removing unprivileged APIs means that
       // some unprivileged APIs may have unrealised dependencies. Too bad!
-      ResolveDependencies(result.get());
-      RemovePrivilegedAPIs(result.get());
+      ResolveDependencies(&temp_result);
+      RemovePrivilegedAPIs(&temp_result);
       break;
 
     case Feature::WEB_PAGE_CONTEXT:
       // Availablility is determined by the url.
       CHECK(url.is_valid());
-      GetAPIsMatchingURL(url, result.get());
+      GetAPIsMatchingURL(url, &temp_result);
       break;
   }
 
+  // Filter out all non-API features and remove the feature type part of the
+  // name.
+  scoped_ptr<std::set<std::string> > result(new std::set<std::string>());
+  for (std::set<std::string>::iterator iter = temp_result.begin();
+       iter != temp_result.end(); ++iter) {
+    std::string feature_type;
+    std::string feature_name;
+    SplitDependencyName(*iter, &feature_type, &feature_name);
+    if (feature_type == "api")
+      result->insert(feature_name);
+  }
+
   return result.Pass();
 }
 
+scoped_ptr<Feature> ExtensionAPI::GetFeature(const std::string& full_name) {
+  // Ensure it's loaded.
+  GetSchema(full_name);
+
+  std::string child_name;
+  std::string api_namespace = GetAPINameFromFullName(full_name, &child_name);
+
+  APIFeatureMap::iterator api_features = features_.find(api_namespace);
+  if (api_features == features_.end())
+    return scoped_ptr<Feature>(NULL);
+
+  scoped_ptr<Feature> result;
+  FeatureMap::iterator child_feature = api_features->second->find(child_name);
+  if (child_feature != api_features->second->end()) {
+    // TODO(aa): Argh, having FeatureProvider return a scoped pointer was a
+    // mistake. See: crbug.com/120068.
+    result.reset(new Feature(*child_feature->second));
+  } else {
+    FeatureMap::iterator parent_feature = api_features->second->find("");
+    CHECK(parent_feature != api_features->second->end());
+    result.reset(new Feature(*parent_feature->second));
+  }
+
+  if (result->contexts()->empty()) {
+    result.reset();
+    LOG(ERROR) << "API feature '" << full_name
+               << "' must specify at least one context.";
+  }
+
+  return result.Pass();
+}
+
+scoped_ptr<Feature> ExtensionAPI::GetFeatureDependency(
+    const std::string& full_name) {
+  std::string feature_type;
+  std::string feature_name;
+  SplitDependencyName(full_name, &feature_type, &feature_name);
+
+  FeatureProviderMap::iterator provider =
+      dependency_providers_.find(feature_type);
+  CHECK(provider != dependency_providers_.end()) << full_name;
+
+  scoped_ptr<Feature> feature(provider->second->GetFeature(feature_name));
+  CHECK(feature.get()) << full_name;
+
+  return feature.Pass();
+}
+
+std::string ExtensionAPI::GetAPINameFromFullName(const std::string& full_name,
+                                                 std::string* child_name) {
+  std::string api_name_candidate = full_name;
+  while (true) {
+    if (features_.find(api_name_candidate) != features_.end() ||
+        schemas_.find(api_name_candidate) != schemas_.end() ||
+        unloaded_schemas_.find(api_name_candidate) != unloaded_schemas_.end()) {
+      std::string result = api_name_candidate;
+
+      if (child_name) {
+        if (result.length() < full_name.length())
+          *child_name = full_name.substr(result.length() + 1);
+        else
+          *child_name = "";
+      }
+
+      return result;
+    }
+
+    size_t last_dot_index = api_name_candidate.rfind('.');
+    if (last_dot_index == std::string::npos)
+      break;
+
+    api_name_candidate = api_name_candidate.substr(0, last_dot_index);
+  }
+
+  *child_name = "";
+  return "";
+}
+
 void ExtensionAPI::GetAllowedAPIs(
     const Extension* extension, std::set<std::string>* out) {
   for (SchemaMap::const_iterator i = schemas_.begin(); i != schemas_.end();
       ++i) {
+    if (features_.find(i->first) != features_.end()) {
+      // This API is controlled by the feature system. Nothing to do here.
+      continue;
+    }
+
     if (extension->required_permission_set()->HasAnyAccessToAPI(i->first) ||
         extension->optional_permission_set()->HasAnyAccessToAPI(i->first)) {
       out->insert(i->first);
     }
   }
 }
 
 void ExtensionAPI::ResolveDependencies(std::set<std::string>* out) {
   std::set<std::string> missing_dependencies;
   for (std::set<std::string>::iterator i = out->begin(); i != out->end(); ++i)
     GetMissingDependencies(*i, *out, &missing_dependencies);
 
   while (missing_dependencies.size()) {
     std::string next = *missing_dependencies.begin();
     missing_dependencies.erase(next);
     out->insert(next);
     GetMissingDependencies(next, *out, &missing_dependencies);
   }
 }
 
 void ExtensionAPI::GetMissingDependencies(
     const std::string& api_name,
     const std::set<std::string>& excluding,
     std::set<std::string>* out) {
-  const DictionaryValue* schema = GetSchema(api_name);
-  CHECK(schema) << "Schema for " << api_name << " not found";
+  std::string feature_type;
+  std::string feature_name;
+  SplitDependencyName(api_name, &feature_type, &feature_name);
+
+  // Only API features can have dependencies for now.
+  if (feature_type != "api")
+    return;
+
+  const DictionaryValue* schema = GetSchema(feature_name);
+  CHECK(schema) << "Schema for " << feature_name << " not found";
 
   ListValue* dependencies = NULL;
   if (!schema->GetList("dependencies", &dependencies))
     return;
 
   for (size_t i = 0; i < dependencies->GetSize(); ++i) {
-    std::string api_name;
-    if (dependencies->GetString(i, &api_name) && !excluding.count(api_name))
-      out->insert(api_name);
+    std::string dependency_name;
+    if (dependencies->GetString(i, &dependency_name) &&
+        !excluding.count(dependency_name)) {
+      out->insert(dependency_name);
+    }
   }
 }
 
 void ExtensionAPI::RemovePrivilegedAPIs(std::set<std::string>* apis) {
   std::set<std::string> privileged_apis;
   for (std::set<std::string>::iterator i = apis->begin(); i != apis->end();
       ++i) {
     if (!completely_unprivileged_apis_.count(*i) &&
         !partially_unprivileged_apis_.count(*i)) {
       privileged_apis.insert(*i);
     }
   }
   for (std::set<std::string>::iterator i = privileged_apis.begin();
       i != privileged_apis.end(); ++i) {
     apis->erase(*i);
   }
 }
 
 void ExtensionAPI::GetAPIsMatchingURL(const GURL& url,
                                       std::set<std::string>* out) {
   for (std::map<std::string, URLPatternSet>::const_iterator i =
       url_matching_apis_.begin(); i != url_matching_apis_.end(); ++i) {
+    if (features_.find(i->first) != features_.end()) {
+      // This API is controlled by the feature system. Nothing to do.
+      continue;
+    }
+
     if (i->second.MatchesURL(url))
       out->insert(i->first);
   }
 }
 
 void ExtensionAPI::LoadAllSchemas() {
   while (unloaded_schemas_.size()) {
     LoadSchema(unloaded_schemas_.begin()->second);
   }
 }
 
 }  // namespace extensions