Mac: Partially enable partial swap

content/common/gpu/image_transport_surface_fbo_mac.mm

 // Copyright 2014 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 "content/common/gpu/image_transport_surface_fbo_mac.h"
 
 #include "content/common/gpu/gpu_messages.h"
 #include "content/common/gpu/image_transport_surface_calayer_mac.h"
 #include "content/common/gpu/image_transport_surface_iosurface_mac.h"
 #include "ui/base/cocoa/remote_layer_api.h"
@@ skipping 151 matching lines @@
   if (!backbuffer_suggested_allocation_ &&
       !frontbuffer_suggested_allocation_ &&
       has_complete_framebuffer_) {
     DestroyFramebuffer();
   } else if (backbuffer_suggested_allocation_ && !has_complete_framebuffer_) {
     AllocateOrResizeFramebuffer(pixel_size_, scale_factor_);
   }
 }
 
 bool ImageTransportSurfaceFBO::SwapBuffers() {
+  return SwapBuffersInternal();
+}
+
+bool ImageTransportSurfaceFBO::SwapBuffersInternal() {
   DCHECK(backbuffer_suggested_allocation_);
   if (!frontbuffer_suggested_allocation_)
     return true;
   glFlush();
 
   // It is the responsibility of the storage provider to send the swap IPC.
   is_swap_buffers_send_pending_ = true;
-  storage_provider_->SwapBuffers(pixel_size_, scale_factor_);
+  storage_provider_->SwapBuffers();
 
   // The call to swapBuffers could potentially result in an immediate draw.
   // Ensure that any changes made to the context's state are restored.
   context_->RestoreStateIfDirtiedExternally();
   return true;
 }
 
 void ImageTransportSurfaceFBO::SendSwapBuffers(uint64 surface_handle,
                                                const gfx::Size pixel_size,
                                                float scale_factor) {
   GpuHostMsg_AcceleratedSurfaceBuffersSwapped_Params params;
   params.surface_handle = surface_handle;
   params.size = pixel_size;
   params.scale_factor = scale_factor;
   params.latency_info.swap(latency_info_);
   helper_->SendAcceleratedSurfaceBuffersSwapped(params);
   is_swap_buffers_send_pending_ = false;
 }
 
 void ImageTransportSurfaceFBO::SetRendererID(int renderer_id) {
   if (renderer_id)
     context_->share_group()->SetRendererID(renderer_id);
 }
 
 bool ImageTransportSurfaceFBO::PostSubBuffer(
     int x, int y, int width, int height) {
-  // Mac does not support sub-buffer swaps.
-  NOTREACHED();
-  return false;
+  return SwapBuffersInternal();
 }
 
 bool ImageTransportSurfaceFBO::SupportsPostSubBuffer() {
-  return false;
+  return true;
 }
 
 gfx::Size ImageTransportSurfaceFBO::GetSize() {
   return pixel_size_;
 }
 
 void* ImageTransportSurfaceFBO::GetHandle() {
   return NULL;
 }
 
@@ skipping 72 matching lines @@
   bool needs_new_storage =
       !has_complete_framebuffer_ ||
       new_rounded_pixel_size != rounded_pixel_size_ ||
       new_scale_factor != scale_factor_;
 
   // Save the new storage parameters.
   pixel_size_ = new_pixel_size;
   rounded_pixel_size_ = new_rounded_pixel_size;
   scale_factor_ = new_scale_factor;
 
-  if (!needs_new_storage)
+  if (!needs_new_storage) {
+    storage_provider_->FrameSizeChanged(pixel_size_, scale_factor_);
     return;
+  }
 
   TRACE_EVENT2("gpu", "ImageTransportSurfaceFBO::AllocateOrResizeFramebuffer",
                "width", new_rounded_pixel_size.width(),
                "height", new_rounded_pixel_size.height());
 
   // GL_TEXTURE_RECTANGLE_ARB is the best supported render target on
   // Mac OS X and is required for IOSurface interoperability.
   GLint previous_texture_id = 0;
 
   GLenum texture_target = GL_TEXTURE_RECTANGLE_ARB;
@@ skipping 74 matching lines @@
   }
 
   GLenum status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
   if (status != GL_FRAMEBUFFER_COMPLETE_EXT) {
     DLOG(ERROR) << "Framebuffer was incomplete: " << status;
     DestroyFramebuffer();
     return;
   }
 
   has_complete_framebuffer_ = true;
+  storage_provider_->FrameSizeChanged(pixel_size_, scale_factor_);
 
   glBindTexture(texture_target, previous_texture_id);
   // The FBO remains bound for this GL context.
 }
 
 }  // namespace content