Remove GSC usage from ExynosVideoDecodeAccelerator.

cc/layers/video_layer_impl.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/layers/video_layer_impl.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "cc/layers/quad_sink.h"
 #include "cc/layers/video_frame_provider_client_impl.h"
@@ skipping 196 matching lines @@
                            SK_ColorTRANSPARENT,
                            opacity,
                            flipped);
       quad_sink->Append(texture_quad.PassAs<DrawQuad>(), append_quads_data);
       break;
     }
     case VideoFrameExternalResources::STREAM_TEXTURE_RESOURCE: {
       DCHECK_EQ(frame_resources_.size(), 1u);
       if (frame_resources_.size() < 1u)
         break;
-      gfx::Transform transform(
-          provider_client_impl_->stream_texture_matrix());
-      transform.Scale(tex_width_scale, tex_height_scale);
+      gfx::Transform scale;

[danakj, 2013/11/13 23:27:19]

I think the old code would be preferable.

This initializes an identity matrix, then scales it, then multiplies it.

The old code initializes a matrx from the stream texture, then scales it. Avoids
the identity step and the extra multiply.

[sheu, 2013/11/13 23:37:34]

Unfortunately, the two operations are not identical, which is why I had to put
this in :-(

What we need for sampling the stream texture is to do a stream texture transform
("T" matrix below), then a scale ("S" matrix below).  So:

  (u', v') = S * T * (u, v)

gfx::Transform::Scale() is a little backwards.  It has this comment:

  // Applies the current transformation on a scaling and assigns the result
  // to |this|.
  void Scale(SkMScalar x, SkMScalar y);

and does a SkMatrix44::preScale(), instead of an SkMatrix44::postScale().  So
what we get incorrectly is:

  (u', v') = T * S * (u, v)

It's a little confusing.

+      scale.Scale(tex_width_scale, tex_height_scale);
       scoped_ptr<StreamVideoDrawQuad> stream_video_quad =
           StreamVideoDrawQuad::Create();
-      stream_video_quad->SetNew(shared_quad_state,
-                                quad_rect,
-                                opaque_rect,
-                                frame_resources_[0],
-                                transform);
+      stream_video_quad->SetNew(
+          shared_quad_state,
+          quad_rect,
+          opaque_rect,
+          frame_resources_[0],
+          scale * provider_client_impl_->stream_texture_matrix());
       quad_sink->Append(stream_video_quad.PassAs<DrawQuad>(),
                         append_quads_data);
       break;
     }
     case VideoFrameExternalResources::IO_SURFACE: {
       DCHECK_EQ(frame_resources_.size(), 1u);
       if (frame_resources_.size() < 1u)
         break;
       gfx::Size visible_size(visible_rect.width(), visible_rect.height());
       scoped_ptr<IOSurfaceDrawQuad> io_surface_quad =
@@ skipping 72 matching lines @@
 void VideoLayerImpl::SetProviderClientImpl(
     scoped_refptr<VideoFrameProviderClientImpl> provider_client_impl) {
   provider_client_impl_ = provider_client_impl;
 }
 
 const char* VideoLayerImpl::LayerTypeAsString() const {
   return "cc::VideoLayerImpl";
 }
 
 }  // namespace cc