Implement actually decoding frames in VTVideoDecodeAccelerator.

content/common/gpu/media/gpu_video_decode_accelerator.cc

Index: content/common/gpu/media/gpu_video_decode_accelerator.cc
diff --git a/content/common/gpu/media/gpu_video_decode_accelerator.cc b/content/common/gpu/media/gpu_video_decode_accelerator.cc
index 0d315dae4e88cd427753086637e79888ba9f4c8f..6ce9330f8c2c75593230205ad408966382cc03b5 100644
--- a/content/common/gpu/media/gpu_video_decode_accelerator.cc
+++ b/content/common/gpu/media/gpu_video_decode_accelerator.cc
@@ -370,11 +370,12 @@ void GpuVideoDecodeAccelerator::OnAssignPictureBuffers(
       NotifyError(media::VideoDecodeAccelerator::INVALID_ARGUMENT);
       return;
     }
-    if (texture_target_ == GL_TEXTURE_EXTERNAL_OES) {
-      // GL_TEXTURE_EXTERNAL_OES textures have their dimensions defined by the
-      // underlying EGLImage.  Use |texture_dimensions_| for this size.
+    if (texture_target_ == GL_TEXTURE_EXTERNAL_OES ||
+        texture_target_ == GL_TEXTURE_RECTANGLE) {
+      // These textures have their dimensions defined by the underlying storage.
+      // Use |texture_dimensions_| for this size.
       texture_manager->SetLevelInfo(texture_ref,
-                                    GL_TEXTURE_EXTERNAL_OES,
+                                    texture_target_,
                                     0,
                                     0,
                                     texture_dimensions_.width(),