[Video] MediaSession API event handlers can resume background video.

content/renderer/media/renderer_webmediaplayer_delegate.cc

 // 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.
 
 #include "content/renderer/media/renderer_webmediaplayer_delegate.h"
 
 #include <stdint.h>
 
 #include "base/auto_reset.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/user_metrics_action.h"
 #include "base/sys_info.h"
 #include "content/common/media/media_player_delegate_messages.h"
 #include "content/public/renderer/render_frame.h"
 #include "content/public/renderer/render_thread.h"
+#include "media/base/media_switches.h"
 #include "third_party/WebKit/public/platform/WebMediaPlayer.h"
+#include "third_party/WebKit/public/web/WebUserGestureIndicator.h"
 
 #if defined(OS_ANDROID)
 #include "base/android/build_info.h"
 #endif
 
 namespace {
 
 void RecordAction(const base::UserMetricsAction& action) {
   content::RenderThread::Get()->RecordAction(action);
 }
@@ skipping 28 matching lines @@
     return true;
 
   return (render_frame() && render_frame()->IsHidden()) || is_frame_closed_;
 }
 
 bool RendererWebMediaPlayerDelegate::IsFrameClosed() {
   return is_frame_closed_;
 }
 
 bool RendererWebMediaPlayerDelegate::IsBackgroundVideoPlaybackUnlocked() {
-  // TODO(sandersd): Include a check for kResumeBackgroundVideo?
-  return background_video_allowed_;
+  return base::FeatureList::IsEnabled(kResumeBackgroundVideo) &&
+         (background_video_allowed_ ||
+          blink::WebUserGestureIndicator::isProcessingUserGesture());
 }
 
 int RendererWebMediaPlayerDelegate::AddObserver(Observer* observer) {
   return id_map_.Add(observer);
 }
 
 void RendererWebMediaPlayerDelegate::RemoveObserver(int player_id) {
   DCHECK(id_map_.Lookup(player_id));
   id_map_.Remove(player_id);
   idle_player_map_.erase(player_id);
@@ skipping 14 matching lines @@
   DVLOG(2) << __func__ << "(" << player_id << ", " << has_video << ", "
            << has_audio << ", " << static_cast<int>(media_content_type) << ")";
   DCHECK(id_map_.Lookup(player_id));
 
   has_played_media_ = true;
   if (has_video) {
     if (!playing_videos_.count(player_id)) {
       playing_videos_.insert(player_id);
       has_played_video_ = true;
     }
+    if (IsFrameHidden() && !IsFrameClosed())
+      background_video_allowed_ = true;
   } else {
     playing_videos_.erase(player_id);
   }
 
   Send(new MediaPlayerDelegateHostMsg_OnMediaPlaying(
       routing_id(), player_id, has_video, has_audio, false,
       media_content_type));
 
   ScheduleUpdateTask();
 }
 
 void RendererWebMediaPlayerDelegate::DidPause(int player_id) {
   DVLOG(2) << __func__ << "(" << player_id << ")";
   DCHECK(id_map_.Lookup(player_id));
+
+  // If user explicitly paused the video playing in the background, don't allow
+  // the page to resume background playback without user's intent.
+  if (blink::WebUserGestureIndicator::isProcessingUserGesture() &&
+      playing_videos_.count(player_id) && IsFrameHidden() && !IsFrameClosed()) {

[DaleCurtis, 2017/02/16 02:47:38]

Is playing_videos_.count() what you want? If the page cycles to paused before
the user hits pause you won't actually disable background video and the next
playlist entry could soon start.

[whywhat, 2017/02/16 13:19:31]

If the page is paused, the user shouldn't be able to pause it again?
Since we don't check for this in OnMediaDelegatePause anymore, should be safe to
remove.

+    background_video_allowed_ = false;
+  }
+
   playing_videos_.erase(player_id);
   Send(new MediaPlayerDelegateHostMsg_OnMediaPaused(routing_id(), player_id,
                                                     false));
 
   // Required to keep background playback statistics up to date.
   ScheduleUpdateTask();
 }
 
 void RendererWebMediaPlayerDelegate::PlayerGone(int player_id) {
   DVLOG(2) << __func__ << "(" << player_id << ")";
@@ skipping 239 matching lines @@
       player->OnIdleTimeout();
     }
   }
 }
 
 void RendererWebMediaPlayerDelegate::OnDestruct() {
   delete this;
 }
 
 }  // namespace media