Added UMA stats for extensions events on addListener.

chrome/browser/extensions/extension_event_histogram_value.h

Index: chrome/browser/extensions/extension_event_histogram_value.h
diff --git a/chrome/browser/extensions/extension_event_histogram_value.h b/chrome/browser/extensions/extension_event_histogram_value.h
new file mode 100644
index 0000000000000000000000000000000000000000..d7d193a692e0a15d8ee639a3037842421cc7482d
--- /dev/null
+++ b/chrome/browser/extensions/extension_event_histogram_value.h
@@ -0,0 +1,181 @@
+// Copyright (c) 2013 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.
+
+#ifndef CHROME_BROWSER_EXTENSIONS_EXTENSION_EVENT_HISTOGRAM_VALUE_H_
+#define CHROME_BROWSER_EXTENSIONS_EXTENSION_EVENT_HISTOGRAM_VALUE_H_
+
+
+namespace extensions {
+namespace events {
+
+// Short version:
+//  *Never* reorder or delete entries in the |HistogramValue| enumeration.
+//  When creating a new extension event, add a new entry at the end of the
+//  enum, just prior to ENUM_BOUNDARY.
+//
+// Long version:
+//  This enumeration is used to associate a unique integer value to each
+//  extension event so that their usage can be recorded in histogram charts.
+//  Given we want the values recorded in the these charts to remain stable over
+//  time for comparison purposes, once an entry has been added to the
+//  enumeration, it should never be removed or moved to another spot in the
+//  enum.
+//
+//  Here are instructions how to manage entries depending on what you are trying
+//  to achieve.
+//
+//  1) Creating a new extension event:
+//
+//      Add a new entry at the end of the |HistogramValue| enum. The name of the
+//      entry should follow this algorithm:
+//      a) Take the string value passed as the event_name argument to
+//         EventRouter::AddEventListener.
+//      b) Replace '.' with '_'.
+//      c) Make all letters uppercase.
+//
+//      Example: "tabs.onCreated" -> TABS_ONCREATED
+//
+//  2) Deleting an existing event:
+//
+//      Given an existing entry should *never* be removed from this enumeration,
+//      it is recommended to add a "DELETED_" prefix to the existing entry.
+//
+//  3) Renaming an existing event:
+//
+//      There are 2 options, depending if you want to keep accruing data in the
+//      *existing* histogram stream or in a *new* one.
+//
+//      a) If you want keep recording usages of the extension event in the
+//         *existing* histogram stream, rename the enum entry to match
+//         the new extension event name, following the same naming rule as
+//         mentioned in 1). The enum entry will keep the same underlying integer
+//         value, so the same histogram stream will be used for recording
+//         usages. You will also need to change the API idl/json file to include
+//         a histogram_value property that contains the old event name.
+//
+//      b) If you want start recording usages of the extension event to in a
+//         *new* histogram stream, follow the instructions in step 1) and 2)
+//         above. This will effectively deprecate the old histogram stream and
+//         creates a new one for the new event name.
+//
+enum HistogramValue {
+  UNKNOWN = 0,
+  FONTSETTINGS_ONFONTCHANGED,
+  FONTSETTINGS_ONDEFAULTFONTSIZECHANGED,
+  FONTSETTINGS_ONDEFAULTFIXEDFONTSIZECHANGED,
+  FONTSETTINGS_ONMINIMUMFONTSIZECHANGED,
+  COOKIES_ONCHANGED,
+  DEBUGGER_ONEVENT,
+  DEBUGGER_ONDETACH,
+  TABS_ONCREATED,
+  TABS_ONUPDATED,
+  TABS_ONMOVED,
+  TABS_ONSELECTIONCHANGED,
+  TABS_ONACTIVECHANGED,
+  TABS_ONACTIVATED,
+  TABS_ONHIGHLIGHTCHANGED,
+  TABS_ONHIGHLIGHTED,
+  TABS_ONDETACHED,
+  TABS_ONATTACHED,
+  TABS_ONREMOVED,
+  TABS_ONREPLACED,
+  SYSTEMINDICATOR_ONCLICKED,
+  SYNCFILESYSTEM_ONSERVICESTATUSCHANGED,
+  SYNCFILESYSTEM_ONFILESTATUSCHANGED,
+  EXPERIMENTAL_ACCESSIBILITY_ONWINDOWOPENED,
+  EXPERIMENTAL_ACCESSIBILITY_ONWINDOWCLOSED,
+  EXPERIMENTAL_ACCESSIBILITY_ONCONTROLFOCUSED,
+  EXPERIMENTAL_ACCESSIBILITY_ONCONTROLACTION,
+  EXPERIMENTAL_ACCESSIBILITY_ONTEXTCHANGED,
+  EXPERIMENTAL_ACCESSIBILITY_ONMENUOPENED,
+  EXPERIMENTAL_ACCESSIBILITY_ONMENUCLOSED,
+  TERMINALPRIVATE_ONPROCESSOUTPUT,
+  BLUETOOTH_ONADAPTERSTATECHANGED,
+  WEBREQUEST_ONBEFOREREQUEST,
+  WEBREQUEST_ONERROROCCURRED,
+  BOOKMARKS_ONCREATED,
+  BOOKMARKS_ONREMOVED,
+  BOOKMARKS_ONCHANGED,
+  BOOKMARKS_ONMOVED,
+  BOOKMARKS_ONCHILDRENREORDERED,
+  BOOKMARKS_ONIMPORTBEGAN,
+  BOOKMARKS_ONIMPORTENDED,
+  CONTEXTMENUS_ONCLICKED,
+  MEDIAPLAYERPRIVATE_ONNEXTTRACK,
+  MEDIAPLAYERPRIVATE_ONPLAYLISTCHANGED,
+  MEDIAPLAYERPRIVATE_ONPREVTRACK,
+  MEDIAPLAYERPRIVATE_ONTOGGLEPLAYSTATE,
+  EXPERIMENTAL_SYSTEMINFO_CPU_ONUPDATED,
+  DIAL_ONDEVICELIST,
+  DIAL_ONERROR,
+  MANAGEMENT_ONINSTALLED,
+  MANAGEMENT_ONUNINSTALLED,
+  MANAGEMENT_ONENABLED,
+  MANAGEMENT_ONDISABLED,
+  WINDOWS_ONCREATED,
+  WINDOWS_ONREMOVED,
+  WINDOWS_ONFOCUSCHANGED,
+  STORAGE_ONCHANGED,
+  PAGELAUNCHER_ONCLICKED,
+  TABCAPTURE_ONSTATUSCHANGED,
+  TEST_ONMESSAGE,
+  WEBNAVIGATION_ONBEFORENAVIGATE,
+  WEBNAVIGATION_ONCOMMITTED,
+  WEBNAVIGATION_ONDOMCONTENTLOADED,
+  WEBNAVIGATION_ONCOMPLETED,
+  WEBNAVIGATION_ONERROROCCURRED,
+  WEBNAVIGATION_ONCREATEDNAVIGATIONTARGET,
+  WEBNAVIGATION_ONREFERENCEFRAGMENTUPDATED,
+  WEBNAVIGATION_ONTABREPLACED,
+  WEBNAVIGATION_ONHISTORYSTATEUPDATED,
+  APP_CURRENTWINDOWINTERNAL_ONCLOSED,
+  APP_CURRENTWINDOWINTERNAL_ONBOUNDSCHANGED,
+  APP_CURRENTWINDOWINTERNAL_ONMINIMIZED,
+  APP_CURRENTWINDOWINTERNAL_ONMAXIMIZED,
+  APP_CURRENTWINDOWINTERNAL_ONRESTORED,
+  MANAGEDMODEPRIVATE_ONCHANGE,
+  PUSHMESSAGING_ONMESSAGE,
+  RTCPRIVATE_ONLAUNCH,
+  DOWNLOADS_ONCREATED,
+  DOWNLOADS_ONERASED,
+  DOWNLOADS_ONCHANGED,
+  NETWORKINGPRIVATE_ONNETWORKSCHANGED,
+  NETWORKINGPRIVATE_ONNETWORKLISTCHANGED,
+  OMNIBOX_ONINPUTSTARTED,
+  OMNIBOX_ONINPUTCHANGED,
+  OMNIBOX_ONINPUTENTERED,
+  OMNIBOX_ONINPUTCANCELLED,
+  SYSTEMINFO_DISPLAY_ONDISPLAYCHANGED,
+  MEDIAGALLERIESPRIVATE_ONDEVICEATTACHED,
+  MEDIAGALLERIESPRIVATE_ONDEVICEDETACHED,
+  MEDIAGALLERIESPRIVATE_ONGALLERYCHANGED,
+  APP_RUNTIME_ONLAUNCHED,
+  APP_RUNTIME_ONRESTARTED,
+  EXTENSION_ONREQUEST,
+  EXTENSION_ONREQUESTEXTERNAL,
+  BOOKMARKMANAGERPRIVATE_ONDRAGENTER,
+  BOOKMARKMANAGERPRIVATE_ONDRAGLEAVE,
+  BOOKMARKMANAGERPRIVATE_ONDROP,
+  SYSTEMPRIVATE_ONVOLUMECHANGED,
+  SYSTEMPRIVATE_ONBRIGHTNESSCHANGED,
+  SYSTEMPRIVATE_ONSCREENUNLOCKED,
+  SYSTEMPRIVATE_ONWOKEUP,
+  IDLE_ONSTATECHANGED,
+  EXPERIMENTAL_NOTIFICATION_ONDISPLAYED,
+  EXPERIMENTAL_NOTIFICATION_ONCLOSED,
+  EXPERIMENTAL_NOTIFICATION_ONCLICKED,
+  EXPERIMENTAL_NOTIFICATION_ONBUTTONCLICKED,
+  EXPERIMENTAL_SYSTEMINFO_STORAGE_ONAVAILABLECAPACITYCHANGED,
+  ALARMS_ONALARM,
+  PERMISSIONS_ONADDED,
+  PERMISSIONS_ONREMOVED,
+  HISTORY_ONVISITED,
+  HISTORY_ONVISITREMOVED,
+  ENUM_BOUNDARY // Last entry: Add new entries above.
+};
+
+}  // namespace events
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_EVENT_HISTOGRAM_VALUE_H_