Do not pause audio only stream when video background play is disabled

For audio only stream, we should let it play even video backgroud play
is disabled.

Bug: internal b/129859403
Test: Move audio only page to background, stream is still playing.
Change-Id: If82d6c0cbc21b71d3da3c8dd70e344b08bdb55f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1552164
Commit-Queue: Yuchen Liu <yucliu@chromium.org>
Reviewed-by: Dan Sanders <sandersd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#650487}

media/blink/webmediaplayer_impl.cc

@@ -3184,16 +3184,19 @@ base::Optional<viz::SurfaceId> WebMediaPlayerImpl::GetSurfaceId() {
   return bridge_->GetSurfaceId();
 }
 
-bool WebMediaPlayerImpl::ShouldPauseVideoWhenHidden() const {
+bool WebMediaPlayerImpl::ShouldPausePlaybackWhenHidden() const {
+  // Audio only stream is allowed to play when in background.
+  // TODO: We should check IsBackgroundOptimizationCandidate here. But we need
+  // to move the logic of checking video frames out of that function.
+  if (!HasVideo())
+    return false;
+
   if (!is_background_video_playback_enabled_)
     return true;
 
   // If suspending background video, pause any video that's not remoted or
   // not unlocked to play in the background.
   if (IsBackgroundSuspendEnabled(this)) {
-    if (!HasVideo())
-      return false;
-
 #if defined(OS_ANDROID)
     if (is_flinging_)
       return false;
@@ -3262,7 +3265,7 @@ bool WebMediaPlayerImpl::IsBackgroundOptimizationCandidate() const {
 
 void WebMediaPlayerImpl::UpdateBackgroundVideoOptimizationState() {
   if (IsHidden()) {
-    if (ShouldPauseVideoWhenHidden()) {
+    if (ShouldPausePlaybackWhenHidden()) {
       PauseVideoIfNeeded();
     } else if (update_background_status_cb_.IsCancelled()) {
       // Only trigger updates when we don't have one already scheduled.

media/blink/webmediaplayer_impl.h

@@ -461,11 +461,11 @@ class MEDIA_BLINK_EXPORT WebMediaPlayerImpl
   // is intended for android.
   bool DoesOverlaySupportMetadata() const;
 
-  // Whether the video should be paused when hidden. Uses metadata so has
+  // Whether the playback should be paused when hidden. Uses metadata so has
   // meaning only after the pipeline has started, otherwise returns false.
-  // Doesn't check if the video can actually be paused depending on the
+  // Doesn't check if the playback can actually be paused depending on the
   // pipeline's state.
-  bool ShouldPauseVideoWhenHidden() const;
+  bool ShouldPausePlaybackWhenHidden() const;
 
   // Whether the video track should be disabled when hidden. Uses metadata so
   // has meaning only after the pipeline has started, otherwise returns false.
@@ -894,7 +894,7 @@ class MEDIA_BLINK_EXPORT WebMediaPlayerImpl
   base::Optional<base::TimeDelta> pipeline_media_duration_for_test_;
 
   // Whether the video requires a user gesture to resume after it was paused in
-  // the background. Affects the value of ShouldPauseVideoWhenHidden().
+  // the background. Affects the value of ShouldPausePlaybackWhenHidden().
   bool video_locked_when_paused_when_hidden_ = false;
 
   // Whether embedded media experience is currently enabled.
@@ -964,7 +964,7 @@ class MEDIA_BLINK_EXPORT WebMediaPlayerImpl
   bool is_background_suspend_enabled_ = false;
 
   // If disabled, video will be auto paused when in background. Affects the
-  // value of ShouldPauseVideoWhenHidden().
+  // value of ShouldPausePlaybackWhenHidden().
   bool is_background_video_playback_enabled_ = true;
 
   // Whether background video optimization is supported on current platform.

media/blink/webmediaplayer_impl_unittest.cc

@@ -1821,8 +1821,8 @@ class WebMediaPlayerImplBackgroundBehaviorTest
     return wmpi_->ShouldDisableVideoWhenHidden();
   }
 
-  bool ShouldPauseVideoWhenHidden() const {
-    return wmpi_->ShouldPauseVideoWhenHidden();
+  bool ShouldPausePlaybackWhenHidden() const {
+    return wmpi_->ShouldPausePlaybackWhenHidden();
   }
 
   bool IsBackgroundOptimizationCandidate() const {
@@ -1837,8 +1837,7 @@ TEST_P(WebMediaPlayerImplBackgroundBehaviorTest, AudioOnly) {
   // Never optimize or pause an audio-only player.
   SetMetadata(true, false);
   EXPECT_FALSE(IsBackgroundOptimizationCandidate());
-  EXPECT_FALSE(IsBackgroundVideoPlaybackEnabled() &&
-               ShouldPauseVideoWhenHidden());
+  EXPECT_FALSE(ShouldPausePlaybackWhenHidden());
   EXPECT_FALSE(ShouldDisableVideoWhenHidden());
 }
 
@@ -1858,7 +1857,7 @@ TEST_P(WebMediaPlayerImplBackgroundBehaviorTest, VideoOnly) {
   bool should_pause = !IsBackgroundVideoPlaybackEnabled() ||
                       IsMediaSuspendOn() ||
                       (IsBackgroundPauseOn() && matches_requirements);
-  EXPECT_EQ(should_pause, ShouldPauseVideoWhenHidden());
+  EXPECT_EQ(should_pause, ShouldPausePlaybackWhenHidden());
 }
 
 TEST_P(WebMediaPlayerImplBackgroundBehaviorTest, AudioVideo) {
@@ -1880,7 +1879,7 @@ TEST_P(WebMediaPlayerImplBackgroundBehaviorTest, AudioVideo) {
   // videos are on by default on Android and off on desktop.
   EXPECT_EQ(!IsBackgroundVideoPlaybackEnabled() ||
                 (IsMediaSuspendOn() && IsResumeBackgroundVideoEnabled()),
-            ShouldPauseVideoWhenHidden());
+            ShouldPausePlaybackWhenHidden());
 
   if (!IsBackgroundOptimizationOn() || !matches_requirements ||
       !ShouldDisableVideoWhenHidden() || IsMediaSuspendOn()) {