Add UMA histogram to track the various sources that request the feedback app

chrome/browser/feedback/show_feedback_page.cc

 // Copyright 2014 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 <string>
 
+#include "base/metrics/histogram_macros.h"
 #include "chrome/browser/extensions/api/feedback_private/feedback_private_api.h"
 #include "chrome/browser/feedback/feedback_dialog_utils.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/chrome_pages.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/browser/ui/webui/md_feedback/md_feedback_dialog_controller.h"
 #include "chrome/common/chrome_switches.h"
 
 namespace chrome {
 
 void ShowFeedbackPage(Browser* browser,
+                      FeedbackSource source,
                       const std::string& description_template,
                       const std::string& category_tag) {
   GURL page_url;
   if (browser) {
     page_url = GetTargetTabUrl(browser->session_id().id(),
                                browser->tab_strip_model()->active_index());
   }
 
   Profile* profile = GetFeedbackProfile(browser);
   if (!profile) {
     LOG(ERROR) << "Cannot invoke feedback: No profile found!";
     return;
   }
 
+  // Record an UMA histogram to know the most frequent feedback request source.
+  UMA_HISTOGRAM_ENUMERATION("Feedback.RequestSource", source,
+                            kFeedbackSourceCount);
+
   if (::switches::MdFeedbackEnabled()) {
     MdFeedbackDialogController::GetInstance()->Show(profile);
     return;
   }
 
   extensions::FeedbackPrivateAPI* api =
       extensions::FeedbackPrivateAPI::GetFactoryInstance()->Get(profile);
 
   api->RequestFeedback(description_template,
                        category_tag,
                        page_url);
 }
 
 }  // namespace chrome