Final batch adding real histogram values for extension events.

chrome/browser/extensions/api/preference/preference_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/browser/extensions/api/preference/preference_api.h"
 
 #include <map>
 #include <utility>
 
 #include "base/lazy_instance.h"
@@ skipping 362 matching lines @@
     return;
   }
 
   dict->Set(keys::kValue, transformed_value);
   if (incognito) {
     ExtensionPrefs* ep = ExtensionPrefs::Get(profile_);
     dict->SetBoolean(keys::kIncognitoSpecific,
                      ep->HasIncognitoPrefValue(browser_pref));
   }
 
-  helpers::DispatchEventToExtensions(profile_,
-                                     event_name,
-                                     &args,
-                                     permission,
-                                     incognito,
+  // TODO(kalman): Have a histogram value for each pref type.
+  // This isn't so important for the current use case of these
+  // histograms, which is to track which event types are waking up event
+  // pages, or which are delivered to persistent background pages. Simply
+  // "a setting changed" is enough detail for that. However if we try to
+  // use these histograms for any fine-grained logic (like removing the
+  // string event name altogether), or if we discover this event is
+  // firing a lot and want to understand that better, then this will need
+  // to change.
+  events::HistogramValue histogram_value =
+      events::TYPES_CHROME_SETTING_ON_CHANGE;
+  helpers::DispatchEventToExtensions(profile_, histogram_value, event_name,
+                                     &args, permission, incognito,
                                      browser_pref);
 }
 
 void PreferenceAPIBase::SetExtensionControlledPref(
     const std::string& extension_id,
     const std::string& pref_key,
     ExtensionPrefsScope scope,
     base::Value* value) {
 #ifndef NDEBUG
   const PrefService::Preference* pref =
@@ skipping 367 matching lines @@
           pref_key, PreferenceFunction::PERMISSION_TYPE_WRITE, &browser_pref)) {
     return false;
   }
 
   PreferenceAPI::Get(GetProfile())
       ->RemoveExtensionControlledPref(extension_id(), browser_pref, scope);
   return true;
 }
 
 }  // namespace extensions