Don't resume paused media. Don't resume playing media after timeout.

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 832433691bd68828415cd0e6ee98628d11754c88..5c0ce9192e0e69a4600e0fdd9142d5fa3f6db2a7 100644
--- a/media/blink/webmediaplayer_impl.cc
+++ b/media/blink/webmediaplayer_impl.cc
@@ -1112,12 +1112,31 @@ void WebMediaPlayerImpl::OnVideoOpacityChange(bool opaque) {
 
 void WebMediaPlayerImpl::OnHidden() {
   DCHECK(main_task_runner_->BelongsToCurrentThread());
+
+  // Don't allow paused players to resume when shown. It's important to check
+  // this here since |delegate_state_| is generally cleared during suspend.

[sandersd (OOO until July 31), 2016/06/07 01:41:16]

It's worth noting here that PAUSED_BUT_NOT_IDLE is purposefully excluded.

+  if (delegate_state_ == DelegateState::PAUSED)
+    is_idle_ = true;
+
+  last_hidden_time_ = base::TimeTicks::Now();
   UpdatePlayState();
 }
 
 void WebMediaPlayerImpl::OnShown() {
   DCHECK(main_task_runner_->BelongsToCurrentThread());
   must_suspend_ = false;
+
+  // Don't auto-resume playback on players that have been idle for some time.
+  // We don't do this when seeking since Blink is waiting for the seeked event
+  // and will get into a bad state if we try and suspend.

[sandersd (OOO until July 31), 2016/06/07 01:41:16]

"try to suspend."

+  if (!paused_ && !seeking_ && !last_hidden_time_.is_null() &&

[sandersd (OOO until July 31), 2016/06/07 01:41:16]

If this is intended to match DelegateState::PAUSED, there are a few more
conditions that UpdatePlayState() checks:

  - !IsNetworkStateError(network_state_)
    We probably shouldn't change the player state when there is an error.

  - !isRemote()
    Same for casting.

  - highest_ready_state_ >= WebMediaPlayer::ReadyStateHaveFutureData
    We want to resume if this isn't true yet.

  - !must_suspend_
    Presumably we don't get OnShown() while the tab is still closed?

  - ready_state_ >= WebMediaPlayer::ReadyStateHaveMetadata
    (Just a clarifies the hasVideo() check, not actually required.)

  - hasVideo()
    We don't want to be pausing audio that is playing.

  - !seeking()
    This is the same as |seeking_| as long as the |ready_state_| check passes.

+      base::TimeTicks::Now() - last_hidden_time_ >
+          base::TimeDelta::FromSeconds(5)) {
+    OnPause();

[sandersd (OOO until July 31), 2016/06/07 01:41:16]

Since OnPause() calls UpdatePlayState(), it's probably better to set |is_idle_|
first.

+    is_idle_ = true;
+  }
+
+  last_hidden_time_ = base::TimeTicks();
   UpdatePlayState();
 }