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

media/blink/webmediaplayer_impl.cc

Index: media/blink/webmediaplayer_impl.cc
diff --git a/media/blink/webmediaplayer_impl.cc b/media/blink/webmediaplayer_impl.cc
index a195bbffe433dd586df6ba14be3dffe79a5891dd..82f021eb57feac1ad0954c592152b681b6e6898d 100644
--- a/media/blink/webmediaplayer_impl.cc
+++ b/media/blink/webmediaplayer_impl.cc
@@ -63,6 +63,7 @@
 #include "third_party/WebKit/public/web/WebDocument.h"
 #include "third_party/WebKit/public/web/WebFrame.h"
 #include "third_party/WebKit/public/web/WebLocalFrame.h"
+#include "third_party/WebKit/public/web/WebUserGestureIndicator.h"
 #include "third_party/WebKit/public/web/WebView.h"
 
 #if defined(OS_ANDROID)
@@ -1962,9 +1963,12 @@ WebMediaPlayerImpl::UpdatePlayState_ComputePlayState(bool is_remote,
   bool is_backgrounded_video = is_backgrounded && have_metadata && hasVideo();
   bool can_play_backgrounded = is_backgrounded_video && !is_remote &&
                                hasAudio() && IsResumeBackgroundVideosEnabled();
-  bool is_background_playing = delegate_->IsBackgroundVideoPlaybackUnlocked();
-  bool background_suspended = !is_streaming && is_backgrounded_video &&
-                              !(can_play_backgrounded && is_background_playing);
+  bool is_background_playing_allowed =

[DaleCurtis, 2017/02/13 22:44:54]

Needs a comment explaining use of the user gesture here.

[sandersd (OOO until July 31), 2017/02/13 22:56:20]

Indeed; the entire design goal of this function is to be stateless, and this is
explicitly stateful. This state should be saved by the caller so that we can
query it without consequence at any time in the future.

[whywhat, 2017/02/14 01:36:28]

Something like play_called_with_user_gesture_ set in play() and then reset in
any other method if there's no user gesture? And call UPS again. This kind of
states are hard to add to WMPI or at least I still haven't wrapped my head
around it :)

[whywhat, 2017/02/15 17:13:12]

I simplified the whole background logic in ComputePlayState now (at the expense
of blocking play() if IsHidden() and ShouldPauseVideoWhenHidden() are both
true).

+      blink::WebUserGestureIndicator::isProcessingUserGesture() ||
+      delegate_->IsBackgroundVideoPlaybackUnlocked();
+  bool background_suspended =
+      !is_streaming && is_backgrounded_video &&
+      !(can_play_backgrounded && is_background_playing_allowed);
   bool background_pause_suspended =
       !is_streaming && is_backgrounded && paused_ && have_future_data;
 
@@ -2099,8 +2103,9 @@ void WebMediaPlayerImpl::FinishMemoryUsageReport(int64_t demuxer_memory_usage) {
 }
 
 void WebMediaPlayerImpl::ScheduleIdlePauseTimer() {
-  // Only schedule the pause timer if we're playing and are suspended.
-  if (paused_ || !pipeline_controller_.IsSuspended())
+  // Only schedule the pause timer if we're not paused or paused but going to
+  // resume when foregrounded, and are suspended.
+  if ((paused_ && !paused_when_hidden_) || !pipeline_controller_.IsSuspended())
     return;
 
 #if defined(OS_ANDROID)
@@ -2148,14 +2153,18 @@ void WebMediaPlayerImpl::ActivateViewportIntersectionMonitoring(bool activate) {
 }
 
 bool WebMediaPlayerImpl::ShouldPauseVideoWhenHidden() const {
-#if !defined(OS_ANDROID)
-  // On desktop, this behavior is behind the feature flag.
-  if (!IsBackgroundVideoTrackOptimizationEnabled())
-    return false;
-#endif
+  if (IsBackgroundedSuspendEnabled()) {
+    // If we intend to pause background videos, pause them as long as
+    // they're not remote or audible and unlocked for background
+    // playback.
+    return hasVideo() && !isRemote() &&
+           (!hasAudio() || !delegate_->IsBackgroundVideoPlaybackUnlocked());
+  }
 
-  // Pause video-only players that match the criteria for being optimized.
-  return !hasAudio() && IsBackgroundOptimizationCandidate();
+  // Otherwise only pause if the optimization is on and it's a video-only
+  // optimization candidate.
+  return IsBackgroundVideoTrackOptimizationEnabled() && !hasAudio() &&
+         IsBackgroundOptimizationCandidate();
 }
 
 bool WebMediaPlayerImpl::ShouldDisableVideoWhenHidden() const {