Fix preserve backbuffer with native GMBs.

gpu/command_buffer/service/gles2_cmd_decoder.cc

 // Copyright (c) 2012 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 "gpu/command_buffer/service/gles2_cmd_decoder.h"
 
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
@@ skipping 384 matching lines @@
   explicit BackTexture(GLES2DecoderImpl* decoder);
   ~BackTexture();
 
   // Create a new render texture.
   void Create();
 
   // Set the initial size and format of a render texture or resize it.
   bool AllocateStorage(const gfx::Size& size, GLenum format, bool zero);
 
   // Copy the contents of the currently bound frame buffer.
-  void Copy(const gfx::Size& size, GLenum format);
+  void Copy();
 
   // Destroy the render texture. This must be explicitly called before
   // destroying this object.
   void Destroy();
 
   // Invalidate the texture. This can be used when a context is lost and it is
   // not possible to make it current in order to free the resource.
   void Invalidate();
 
   // The bind point for the texture.
@@ skipping 2169 matching lines @@
   }
 
   if (success) {
     memory_tracker_.TrackMemFree(bytes_allocated_);
     bytes_allocated_ = image_size;
     memory_tracker_.TrackMemAlloc(bytes_allocated_);
   }
   return success;
 }
 
-void BackTexture::Copy(const gfx::Size& size, GLenum format) {
+void BackTexture::Copy() {
   DCHECK_NE(id(), 0u);
   ScopedGLErrorSuppressor suppressor("BackTexture::Copy",
                                      decoder_->state_.GetErrorState());
   ScopedTextureBinder binder(&decoder_->state_, id(), Target());
-  glCopyTexImage2D(Target(),
-                   0,  // level
-                   format, 0, 0, size.width(), size.height(),
-                   0);  // border
+  glCopyTexSubImage2D(Target(),
+                      0,  // level
+                      0, 0, 0, 0, size_.width(), size_.height());
 }
 
 void BackTexture::Destroy() {
   if (image_) {
     DCHECK(texture_ref_);
     ScopedTextureBinder binder(&decoder_->state_, id(), Target());
     DestroyNativeGpuMemoryBuffer(true);
   }
 
   if (texture_ref_) {
@@ skipping 10858 matching lines @@
 
     if (IsOffscreenBufferMultisampled()) {
       // For multisampled buffers, resolve the frame buffer.
       ScopedResolvedFrameBufferBinder binder(this, true, false);
     } else {
       ScopedFrameBufferBinder binder(this,
                                      offscreen_target_frame_buffer_->id());
 
       if (offscreen_target_buffer_preserved_) {
         // Copy the target frame buffer to the saved offscreen texture.
-        offscreen_saved_color_texture_->Copy(
-            offscreen_saved_color_texture_->size(),
-            offscreen_saved_color_format_);
+        offscreen_saved_color_texture_->Copy();
       } else {
         offscreen_saved_color_texture_.swap(offscreen_target_color_texture_);
         offscreen_target_frame_buffer_->AttachRenderTexture(
             offscreen_target_color_texture_.get());
         offscreen_saved_frame_buffer_->AttachRenderTexture(
             offscreen_saved_color_texture_.get());
       }
 
       // Ensure the side effects of the copy are visible to the parent
       // context. There is no need to do this for ANGLE because it uses a
@@ skipping 3611 matching lines @@
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "base/macros.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu