Adding UMA on page load size for pages with Media

chrome/browser/page_load_metrics/page_load_metrics_observer.h

 // Copyright 2015 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_PAGE_LOAD_METRICS_PAGE_LOAD_METRICS_OBSERVER_H_
 #define CHROME_BROWSER_PAGE_LOAD_METRICS_PAGE_LOAD_METRICS_OBSERVER_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "base/optional.h"
 #include "chrome/common/page_load_metrics/page_load_timing.h"
 #include "content/public/browser/navigation_handle.h"
+#include "content/public/browser/web_contents_observer.h"
 #include "third_party/WebKit/public/platform/WebInputEvent.h"
 #include "url/gurl.h"
 
 namespace page_load_metrics {
 
 // This enum represents how a page load ends. If the action occurs before the
 // page load finishes (or reaches some point like first paint), then we consider
 // the load to be aborted.
 enum PageEndReason {
   // Page lifetime has not yet ended (page is still active).
@@ skipping 292 matching lines @@
   virtual void OnParseStart(const PageLoadTiming& timing,
                             const PageLoadExtraInfo& extra_info) {}
   virtual void OnParseStop(const PageLoadTiming& timing,
                            const PageLoadExtraInfo& extra_info) {}
 
   // Invoked when there is a change in either the main_frame_metadata or the
   // child_frame_metadata's loading behavior_flags.
   virtual void OnLoadingBehaviorObserved(
       const page_load_metrics::PageLoadExtraInfo& extra_info) {}
 
+  // Invoked when a media element starts playing.
+  virtual void MediaStartedPlaying(
+      const content::WebContentsObserver::MediaPlayerInfo& video_type,
+      bool is_in_main_frame) {}
+
   // Invoked when the UMA metrics subsystem is persisting metrics as the
   // application goes into the background, on platforms where the browser
   // process may be killed after backgrounding (Android). Implementers should
   // persist any metrics that have been buffered in memory in this callback, as
   // the application may be killed at any time after this method is invoked
   // without further notification. Note that this may be called both for
   // provisional loads as well as committed loads. Implementations that only
   // want to track committed loads should check whether extra_info.committed_url
   // is empty to determine if the load had committed. If the implementation
   // returns CONTINUE_OBSERVING, this method may be called multiple times per
@@ skipping 27 matching lines @@
       const FailedProvisionalLoadInfo& failed_provisional_load_info,
       const PageLoadExtraInfo& extra_info) {}
 
   // Called whenever a request is loaded for this page load.
   virtual void OnLoadedResource(const ExtraRequestInfo& extra_request_info) {}
 };
 
 }  // namespace page_load_metrics
 
 #endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_PAGE_LOAD_METRICS_OBSERVER_H_