Propogate the tab foreground, background change events to data use

chrome/browser/data_use_measurement/chrome_data_use_ascriber.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_H_
 #define CHROME_BROWSER_DATA_USE_MEASUREMENT_CHROME_DATA_USE_ASCRIBER_H_
 
 #include <list>
 #include <memory>
 #include <string>
@@ skipping 73 matching lines @@
   // Called when a main frame navigation is ready to be committed in a
   // renderer.
   void ReadyToCommitMainFrameNavigation(
       GURL gurl,
       content::GlobalRequestID global_request_id,
       int render_process_id,
       int render_frame_id,
       bool is_same_page_navigation,
       void* navigation_handle);
 
+  // Called every time the WebContents changes visibility.
+  void WasShownOrHidden(int main_render_process_id,
+                        int main_render_frame_id,
+                        bool visible);
+
+  // Called whenever one of the render frames of a WebContents is swapped.
+  void RenderFrameHostChanged(int old_render_process_id,
+                              int old_render_frame_id,
+                              int new_render_process_id,
+                              int new_render_frame_id);
 
  private:
   friend class ChromeDataUseAscriberTest;
 
   // Entry in the |data_use_recorders_| list which owns all instances of
   // DataUseRecorder.
   typedef std::list<ChromeDataUseRecorder> DataUseRecorderList;
   typedef DataUseRecorderList::iterator DataUseRecorderEntry;
 
   struct GlobalRequestIDHash {
@@ skipping 45 matching lines @@
   base::hash_map<RenderFrameHostID, RenderFrameHostID>
       subframe_to_mainframe_map_;
 
   // Map from pending navigations to the DataUseRecorderEntry in
   // |data_use_recorders_| that the navigation ascribes data use to.
   std::unordered_map<content::GlobalRequestID,
                      DataUseRecorderEntry,
                      GlobalRequestIDHash>
       pending_navigation_data_use_map_;
 
+  // Contains the mainframe IDs that are currently visible.
+  base::hash_set<RenderFrameHostID> visible_main_render_frames_;
+
   DISALLOW_COPY_AND_ASSIGN(ChromeDataUseAscriber);
 };
 
 }  // namespace data_use_measurement
 
 #endif  // CHROME_BROWSER_DATA_USE_MEASUREMENT_CHROME_DATA_USE_ASCRIBER_H_