gpu: Make GPU command decoder know right format of a GPU video texture in Win.

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 df8ec5bc0ec8c72f35ba64dea56b0f1952197b62..fc8b4d892a6474c9defd53d68c68c90ea6a2c6a6 100644
--- a/content/common/gpu/media/gpu_video_decode_accelerator.cc
+++ b/content/common/gpu/media/gpu_video_decode_accelerator.cc
@@ -370,19 +370,25 @@ void GpuVideoDecodeAccelerator::OnAssignPictureBuffers(
       NotifyError(media::VideoDecodeAccelerator::INVALID_ARGUMENT);
       return;
     }
+    bool os_win = false;
+    // FIXME: after moving to D3D11, remove this workaround. crbug.com/438691
+#if defined(OS_WIN)
+    os_win = true;
+#endif
     if (texture_target_ == GL_TEXTURE_EXTERNAL_OES ||
-        texture_target_ == GL_TEXTURE_RECTANGLE) {
+        texture_target_ == GL_TEXTURE_RECTANGLE || os_win) {
+      GLenum format = os_win ? GL_BGRA_EXT : GL_RGBA;

[Ken Russell (switch to Gerrit), 2014/12/04 01:25:18]

Please define some sort of API that is overridden by
dxva_video_decode_accelerator.cc to fetch this format, so the use of
D3DFMT_X8R8G8B8 / D3DFMT_A8R8G8B8 and GL_BGRA_EXT are close together.

I'm also concerned that this may not be forward compatible with the OpenGL ES
3.0 upgrade. Is GL_BGRA_EXT a valid internal format? According to
https://www.khronos.org/registry/gles/extensions/APPLE/APPLE_texture_format_B...
-- which is the only BGRA extension that was upgraded for ES 3.0 -- it looks
like it needs to be GL_BGRA8_EXT.

Finally, how much testing has this change undergone? It has the potential to
break video playback in many scenarios -- directly on the page, drawn into 2D
and WebGL canvas contexts -- and I'm very concerned that we don't have enough
test coverage to catch regressions in automated fashion. See
http://crbug.com/436578 .

       // These textures have their dimensions defined by the underlying storage.
       // Use |texture_dimensions_| for this size.
       texture_manager->SetLevelInfo(texture_ref,
                                     texture_target_,
                                     0,
-                                    GL_RGBA,
+                                    format,
                                     texture_dimensions_.width(),
                                     texture_dimensions_.height(),
                                     1,
                                     0,
-                                    GL_RGBA,
+                                    format,
                                     0,
                                     false);
     } else {