Add SurfaceTexture::release and call it from AVDA.

media/gpu/android_deferred_rendering_backing_strategy.cc

Index: media/gpu/android_deferred_rendering_backing_strategy.cc
diff --git a/media/gpu/android_deferred_rendering_backing_strategy.cc b/media/gpu/android_deferred_rendering_backing_strategy.cc
index cd3ed0edf1ba96e547a6bdb48d806a79432c7440..53105fd4713122977ab7f29dc2e42982b08a4a40 100644
--- a/media/gpu/android_deferred_rendering_backing_strategy.cc
+++ b/media/gpu/android_deferred_rendering_backing_strategy.cc
@@ -61,16 +61,28 @@ gl::ScopedJavaSurface AndroidDeferredRenderingBackingStrategy::Initialize(
   return gl::ScopedJavaSurface(surface_texture_.get());
 }
 
-void AndroidDeferredRenderingBackingStrategy::Cleanup(
+void AndroidDeferredRenderingBackingStrategy::BeginCleanup(
     bool have_context,
     const AndroidVideoDecodeAccelerator::OutputBufferMap& buffers) {
   // If we failed before Initialize, then do nothing.
   if (!shared_state_)
     return;
 
+  // TODO(liberato): we should release all codec buffers here without rendering.
+  // CodecChanged() will drop them, but is expected to be called after the codec
+  // is no longer accessible.  It's unclear that VP8 flush in AVDA can't hang
+  // waiting for our buffers.
+
   CodecChanged(nullptr);
 }
 
+void AndroidDeferredRenderingBackingStrategy::EndCleanup() {
+  // Release the surface texture and any back buffers.  This will preserve the
+  // front buffer, if any.
+  if (surface_texture_)
+    surface_texture_->ReleaseSurfaceTexture();

[liberato (no reviews please), 2016/06/24 17:40:20]

i was on the fence about whether we could just do this in Cleanup(), before the
flush completes.  probably it's safe, since we won't be releasing with
rendering.  i was worried that MediaCodec might be doing something weird with
SurfaceTexture back buffers that would quit working.

it definitely seems safe to do after.

+}
+
 scoped_refptr<gl::SurfaceTexture>
 AndroidDeferredRenderingBackingStrategy::GetSurfaceTexture() const {
   return surface_texture_;