Enforce the 'requirements' field in manifests.

chrome/browser/ui/webui/extensions/extension_settings_handler.cc

Index: chrome/browser/ui/webui/extensions/extension_settings_handler.cc
diff --git a/chrome/browser/ui/webui/extensions/extension_settings_handler.cc b/chrome/browser/ui/webui/extensions/extension_settings_handler.cc
index 163ffdf3b8cf918fd8e800834fb2462fbebc9f75..ed1a98f3a6b90098b2ed9e4311b51d63ae0ecd2a 100644
--- a/chrome/browser/ui/webui/extensions/extension_settings_handler.cc
+++ b/chrome/browser/ui/webui/extensions/extension_settings_handler.cc
@@ -10,6 +10,7 @@
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/file_util.h"
+#include "base/string_util.h"
 #include "base/string_number_conversions.h"
 #include "base/utf_string_conversions.h"
 #include "base/values.h"
@@ -18,6 +19,7 @@
 #include "chrome/browser/debugger/devtools_window.h"
 #include "chrome/browser/extensions/crx_installer.h"
 #include "chrome/browser/extensions/extension_disabled_ui.h"
+#include "chrome/browser/extensions/extension_error_reporter.h"
 #include "chrome/browser/extensions/extension_host.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/extension_system.h"
@@ -624,6 +626,18 @@ void ExtensionSettingsHandler::HandleEnableMessage(const ListValue* args) {
           web_ui()->GetWebContents());
       extensions::ShowExtensionDisabledDialog(
           extension_service_, browser, extension);
+    } else if ((prefs->GetDisableReasons(extension_id) &
+                   Extension::DISABLE_UNSUPPORTED_REQUIREMENT) &&
+               !requirements_checker_.get()) {
+      // Recheck the requirements.
+      scoped_refptr<const Extension> extension =
+          extension_service_->GetExtensionById(extension_id,
+                                               true /* include disabled */);
+      requirements_checker_.reset(new extensions::RequirementsChecker());
+      requirements_checker_->Check(
+          extension,
+          base::Bind(&ExtensionSettingsHandler::OnRequirementsChecked,
+                     AsWeakPtr(), extension_id));
     } else {
       extension_service_->EnableExtension(extension_id);
     }
@@ -887,3 +901,16 @@ void ExtensionSettingsHandler::InspectExtensionHost(
   if (host)
     DevToolsWindow::OpenDevToolsWindow(host->render_view_host());
 }
+
+void ExtensionSettingsHandler::OnRequirementsChecked(
+    std::string extension_id,
+    std::vector<std::string> requirement_errors) {
+  if (requirement_errors.empty()) {
+    extension_service_->EnableExtension(extension_id);
+  } else {
+    ExtensionErrorReporter::GetInstance()->ReportError(
+        UTF8ToUTF16(JoinString(requirement_errors, ' ')),
+        true /* be noisy */);
+  }
+  requirements_checker_.reset();
+}