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

content/renderer/media/renderer_webmediaplayer_delegate.cc

Index: content/renderer/media/renderer_webmediaplayer_delegate.cc
diff --git a/content/renderer/media/renderer_webmediaplayer_delegate.cc b/content/renderer/media/renderer_webmediaplayer_delegate.cc
index 92d1140e8a6c52c2500f4daa21383717f482f37d..a20a72e43311cef9b291579286d64c5bbced51b4 100644
--- a/content/renderer/media/renderer_webmediaplayer_delegate.cc
+++ b/content/renderer/media/renderer_webmediaplayer_delegate.cc
@@ -13,7 +13,9 @@
 #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"
@@ -62,8 +64,9 @@ bool RendererWebMediaPlayerDelegate::IsFrameClosed() {
 }
 
 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) {
@@ -98,6 +101,8 @@ void RendererWebMediaPlayerDelegate::DidPlay(
       playing_videos_.insert(player_id);
       has_played_video_ = true;
     }
+    if (IsFrameHidden() && !IsFrameClosed())
+      background_video_allowed_ = true;
   } else {
     playing_videos_.erase(player_id);
   }
@@ -112,6 +117,14 @@ void RendererWebMediaPlayerDelegate::DidPlay(
 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));