Propogate the tab foreground, background change events to data use

chrome/browser/data_use_measurement/chrome_data_use_ascriber_service.h

 // Copyright 2016 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_DATA_USE_MEASUREMENT_CHROME_DATA_USE_ASCRIBER_SERVICE_H_
 #define CHROME_BROWSER_DATA_USE_MEASUREMENT_CHROME_DATA_USE_ASCRIBER_SERVICE_H_
 
 #include <list>
+#include <unordered_set>
 
 #include "base/macros.h"
 #include "components/keyed_service/core/keyed_service.h"
 
 namespace content {
 class NavigationHandle;
 class RenderFrameHost;
 }
 
 namespace data_use_measurement {
@@ skipping 27 matching lines @@
   // Called when a navigation is started. Propagates main frame navigation
   // start to the |ascriber_| on the IO thread. NavigationHandle methods
   // cannot be called on the IO thread, so the pointer is cast to void*.
   void DidStartNavigation(content::NavigationHandle* navigation_handle);
 
   // Called when the navigation is ready to be committed in a renderer.
   // Propagates the event to the |ascriber_| on the IO thread. NavigationHandle
   // methods cannot be called on the IO thread, so the pointer is cast to void*.
   void ReadyToCommitNavigation(content::NavigationHandle* navigation_handle);
 
+  // Called every time the WebContents changes visibility. Propagates the event
+  // to the |ascriber_| on the IO thread.
+  void WasShownOrHidden(content::RenderFrameHost* main_render_frame_host,
+                        bool visible);
+
+  void RenderFrameHostChanged(content::RenderFrameHost* old_host,

[RyanSturm, 2016/12/13 22:04:20]

nit: Can you add a class comment?

[Raj, 2016/12/14 23:00:50]

Done.

+                              content::RenderFrameHost* new_host);
+
  private:
   friend class ChromeDataUseAscriberServiceTest;
 
   void SetDataUseAscriber(ChromeDataUseAscriber* ascriber);
 
   // |ascriber_| outlives this instance.
   ChromeDataUseAscriber* ascriber_;
 
   // Tracks whether |ascriber_| was set. This field is required because tests
   // might set |ascriber_| to nullptr.
   bool is_initialized_;
 
   // Frame events might arrive from the UI thread before |ascriber_| is set. A
   // queue of frame events that arrive before |ascriber_| is set is maintained
   // in this field so that they can be propagated immediately after |ascriber_|
   // is set. The RenderFrameHost pointers in the queues are valid for the
   // duration that they are in the queue.
   std::list<content::RenderFrameHost*> pending_frames_queue_;
 
+  // WebContents visibility change events might arrive from the UI thread before
+  // |ascriber_| is set. Sucn pending main render frame visibile events are
+  // maintained in this set and propagated immediately after |ascriber_| is set.
+  std::unordered_set<content::RenderFrameHost*> pending_visible_main_frames_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeDataUseAscriberService);
 };
 
 }  // namespace data_use_measurement
 
 #endif  // CHROME_BROWSER_DATA_USE_MEASUREMENT_CHROME_DATA_USE_ASCRIBER_SERVICE_H_