Collect UMA data for extension manifest version and background page type.

chrome/browser/extensions/installed_loader.cc

Index: chrome/browser/extensions/installed_loader.cc
diff --git a/chrome/browser/extensions/installed_loader.cc b/chrome/browser/extensions/installed_loader.cc
index 155a177b2b591b59c84a1ad01121c2a7e641dd62..d9de618ff6edb101de0d8c1b0c4db2519724887e 100644
--- a/chrome/browser/extensions/installed_loader.cc
+++ b/chrome/browser/extensions/installed_loader.cc
@@ -20,6 +20,7 @@
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/api/managed_mode_private/managed_mode_handler.h"
+#include "chrome/common/extensions/background_info.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/extension_file_util.h"
 #include "chrome/common/extensions/extension_l10n_util.h"
@@ -37,6 +38,8 @@ using extensions::Manifest;
 
 namespace errors = extension_manifest_errors;
 
+namespace extensions {
+
 namespace {
 
 // The following enumeration is used in histograms matching
@@ -49,6 +52,14 @@ enum ManifestReloadReason {
   NUM_MANIFEST_RELOAD_REASONS
 };
 
+// Used in histogram Extension.BackgroundPageType. Values may be added, as
+// long as existing values are not changed.
+enum BackgroundPageType {
+  NO_BACKGROUND_PAGE = 0,
+  BACKGROUND_PAGE_PERSISTENT = 1,
+  EVENT_PAGE = 2,
+};
+
 ManifestReloadReason ShouldReloadExtensionManifest(const ExtensionInfo& info) {
   // Always reload manifests of unpacked extensions, because they can change
   // on disk independent of the manifest in our prefs.
@@ -63,6 +74,14 @@ ManifestReloadReason ShouldReloadExtensionManifest(const ExtensionInfo& info) {
   return NOT_NEEDED;
 }
 
+BackgroundPageType GetBackgroundPageType(const Extension* extension) {
+  if (!BackgroundInfo::HasBackgroundPage(extension))
+    return NO_BACKGROUND_PAGE;
+  if (BackgroundInfo::HasPersistentBackgroundPage(extension))
+    return BACKGROUND_PAGE_PERSISTENT;
+  return EVENT_PAGE;
+}
+
 void DispatchOnInstalledEvent(
     Profile* profile,
     const std::string& extension_id,
@@ -80,8 +99,6 @@ void DispatchOnInstalledEvent(
 
 }  // namespace
 
-namespace extensions {
-
 InstalledLoader::InstalledLoader(ExtensionService* extension_service)
     : extension_service_(extension_service),
       extension_prefs_(extension_service->extension_prefs()) {
@@ -281,6 +298,15 @@ void InstalledLoader::LoadAllExtensions() {
     if (Manifest::IsUnpackedLocation(location))
       continue;
 
+    UMA_HISTOGRAM_ENUMERATION("Extensions.ManifestVersion",
+                              (*ex)->manifest_version(), 10);
+
+    if (type == Manifest::TYPE_EXTENSION) {
+      BackgroundPageType background_page_type = GetBackgroundPageType(*ex);
+      UMA_HISTOGRAM_ENUMERATION("Extensions.BackgroundPageType",
+                                background_page_type, 10);
+    }
+
     // Using an enumeration shows us the total installed ratio across all users.
     // Using the totals per user at each startup tells us the distribution of
     // usage for each user (e.g. 40% of users have at least one app installed).