Media latencyHint: Fix crash if >0 set before init

latencyHint should be settable at any point, especially early.

This change removes the assumption that VRI algorithm_ is set prior to
latencyHint.

Bug: 1114748, 1100555
Change-Id: I69a0916674b1575547faab4fda371eb81bbea7ee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2370653Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Chrome Cunningham <chcunningham@chromium.org>
Auto-Submit: Chrome Cunningham <chcunningham@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801179}

media/renderers/video_renderer_impl.cc

@@ -490,13 +490,17 @@ void VideoRendererImpl::SetLatencyHint(
         << "Video latency hint set:" << *latency_hint << ". "
         << "Effective buffering latency: 1 frame";
   } else {
-    // Non-zero latency hints are set here. This method will also be called
-    // for each frame in case |average_frame_druation| changes, facilitating
-    // re-computation of how many frames we should buffer to achieve the target
-    // latency. |is_latency_hint_media_logged_| ensures that we only MEDIA_LOG
-    // on the first application of this hint.
+    // Non-zero latency hints are set here. Update buffering caps immediately if
+    // we already have an algorithm_. Otherwise, the update will be applied as
+    // frames arrive and duration becomes known. The caps will be recalculated
+    // for each frame in case |average_frame_druation| changes.
+    // |is_latency_hint_media_logged_| ensures that we only MEDIA_LOG on the
+    // first application of this hint.
     is_latency_hint_media_logged_ = false;
-    UpdateLatencyHintBufferingCaps_Locked(algorithm_->average_frame_duration());
+    if (algorithm_) {
+      UpdateLatencyHintBufferingCaps_Locked(
+          algorithm_->average_frame_duration());
+    }
   }
 }
 

media/renderers/video_renderer_impl_unittest.cc

@@ -1497,8 +1497,6 @@ TEST_F(VideoRendererLatencyHintTest, HaveEnough_LowLatencyHint) {
 
 // Test late HaveEnough transition when high latency hint is set.
 TEST_F(VideoRendererLatencyHintTest, HaveEnough_HighLatencyHint) {
-  Initialize();
-
   // We must provide a |buffer_duration_| for the latencyHint to take effect
   // immediately. The VideoRendererAlgorithm will eventually provide a PTS-delta
   // duration, but not until after we've started rendering.
@@ -1507,6 +1505,12 @@ TEST_F(VideoRendererLatencyHintTest, HaveEnough_HighLatencyHint) {
   // Set latencyHint to a large value.
   renderer_->SetLatencyHint(base::TimeDelta::FromMilliseconds(400));
 
+  // NOTE: other tests will SetLatencyHint after Initialize(). Either way should
+  // work. Initializing later is especially interesting for "high" hints because
+  // the renderer will try to set buffering caps based on stream state that
+  // isn't yet available.
+  Initialize();
+
   // Initial frames should trigger various callbacks.
   EXPECT_CALL(mock_cb_, FrameReceived(HasTimestampMatcher(0)));
   EXPECT_CALL(mock_cb_, OnVideoNaturalSizeChange(_)).Times(1);