[Video] Pause videos with no audio when in the background.

media/blink/webmediaplayer_impl.cc

 // Copyright 2013 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 "media/blink/webmediaplayer_impl.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 #include <string>
@@ skipping 187 matching lines @@
           &pipeline_,
           base::Bind(&WebMediaPlayerImpl::CreateRenderer,
                      base::Unretained(this)),
           base::Bind(&WebMediaPlayerImpl::OnPipelineSeeked, AsWeakPtr()),
           base::Bind(&WebMediaPlayerImpl::OnPipelineSuspended, AsWeakPtr()),
           base::Bind(&WebMediaPlayerImpl::OnError, AsWeakPtr())),
       load_type_(LoadTypeURL),
       opaque_(false),
       playback_rate_(0.0),
       paused_(true),
+      paused_when_hidden_(false),
       seeking_(false),
       pending_suspend_resume_cycle_(false),
       ended_(false),
       should_notify_time_changed_(false),
       overlay_enabled_(false),
       decoder_requires_restart_for_overlay_(false),
       client_(client),
       encrypted_client_(encrypted_client),
       delegate_(delegate),
       delegate_id_(0),
@@ skipping 223 matching lines @@
 
 void WebMediaPlayerImpl::pause() {
   DVLOG(1) << __func__;
   DCHECK(main_task_runner_->BelongsToCurrentThread());
 
   // We update the paused state even when casting, since we expect pause() to be
   // called when casting begins, and when we exit casting we should end up in a
   // paused state.
   paused_ = true;
 
+  // No longer paused because it was hidden.
+  paused_when_hidden_ = false;
+
 #if defined(OS_ANDROID)  // WMPI_CAST
   if (isRemote()) {
     cast_impl_.pause();
     return;
   }
 #endif
 
   pipeline_.SetPlaybackRate(0.0);
 
   // pause() may be called after playback has ended and the HTMLMediaElement
@@ skipping 868 matching lines @@
   opaque_ = opaque;
   // Modify content opaqueness of cc::Layer directly so that
   // SetContentsOpaqueIsFixed is ignored.
   if (video_weblayer_)
     video_weblayer_->layer()->SetContentsOpaque(opaque_);
 }
 
 void WebMediaPlayerImpl::OnHidden() {
   DCHECK(main_task_runner_->BelongsToCurrentThread());
 
-  if (IsBackgroundVideoTrackOptimizationEnabled())
-    selectedVideoTrackChanged(nullptr);
-
   if (watch_time_reporter_)
     watch_time_reporter_->OnHidden();
 
+  if (IsBackgroundVideoTrackOptimizationEnabled()) {
+    if (ShouldPauseWhenHidden()) {
+      OnPause();
+      paused_when_hidden_ = true;

[sandersd (OOO until July 31), 2017/01/06 01:44:15]

Probably needs a comment to explain that the order of these lines is important.

This is also relying on pause() to call UpdatePlayState(), which works, but
isn't obvious.

[whywhat, 2017/01/06 16:59:31]

Done. Alternatively I could perhaps take the most of pause() into its own method
(pause_internal() ?) and call that along with setting the flag, calling
UpdatePlayState() and client_->UpdatePlayState() -- sounds like some duplication
but no hidden dependencies. OnPause() call below would need something similar
too though.

+      return;
+    }
+
+    selectedVideoTrackChanged(nullptr);
+  }
+
   UpdatePlayState();
 
   // Schedule suspended playing media to be paused if the user doesn't come back
   // to it within some timeout period to avoid any autoplay surprises.
   ScheduleIdlePauseTimer();
 }
 
 void WebMediaPlayerImpl::OnShown() {
   DCHECK(main_task_runner_->BelongsToCurrentThread());
   if (watch_time_reporter_)
     watch_time_reporter_->OnShown();
 
-  if (IsBackgroundVideoTrackOptimizationEnabled() &&
-      client_->hasSelectedVideoTrack()) {
-    WebMediaPlayer::TrackId trackId = client_->getSelectedVideoTrackId();
-    selectedVideoTrackChanged(&trackId);
+  if (IsBackgroundVideoTrackOptimizationEnabled()) {
+    if (paused_when_hidden_) {
+      paused_when_hidden_ = false;
+      OnPlay();
+      return;
+    }
+
+    if (client_->hasSelectedVideoTrack()) {
+      WebMediaPlayer::TrackId trackId = client_->getSelectedVideoTrackId();
+      selectedVideoTrackChanged(&trackId);
+    }
   }
 
   must_suspend_ = false;
   background_pause_timer_.Stop();
 
   UpdatePlayState();
 }
 
 bool WebMediaPlayerImpl::OnSuspendRequested(bool must_suspend) {
   DCHECK(main_task_runner_->BelongsToCurrentThread());
@@ skipping 662 matching lines @@
 bool WebMediaPlayerImpl::DoesOverlaySupportMetadata() const {
   return pipeline_metadata_.video_rotation == VIDEO_ROTATION_0;
 }
 
 void WebMediaPlayerImpl::ActivateViewportIntersectionMonitoring(bool activate) {
   DCHECK(main_task_runner_->BelongsToCurrentThread());
 
   client_->activateViewportIntersectionMonitoring(activate);
 }
 
+bool WebMediaPlayerImpl::ShouldPauseWhenHidden() const {
+#if defined(OS_ANDROID)  // WMPI_CAST
+  if (isRemote())
+    return false;
+#endif  // defined(OS_ANDROID)  // WMPI_CAST
+
+  return hasVideo() && !hasAudio();
+}
+
 }  // namespace media