Enable partial texture upload support for browser compositor with Surfaces

content/browser/compositor/surface_display_output_surface.cc

 // 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/browser/compositor/surface_display_output_surface.h"
 
 #include "cc/output/compositor_frame.h"
 #include "cc/output/compositor_frame_ack.h"
 #include "cc/surfaces/display.h"
 #include "cc/surfaces/surface.h"
 #include "cc/surfaces/surface_manager.h"
 #include "content/browser/compositor/onscreen_display_client.h"
 
 namespace content {
 
 SurfaceDisplayOutputSurface::SurfaceDisplayOutputSurface(
     cc::SurfaceManager* surface_manager,
     cc::SurfaceIdAllocator* allocator,
     const scoped_refptr<cc::ContextProvider>& context_provider)
     : cc::OutputSurface(context_provider,
                         scoped_ptr<cc::SoftwareOutputDevice>()),
       display_client_(NULL),
       surface_manager_(surface_manager),
       factory_(surface_manager, this),
       allocator_(allocator) {
   capabilities_.delegated_rendering = true;
   capabilities_.max_frames_pending = 1;
+  capabilities_.can_force_reclaim_resources = true;
 }
 
 SurfaceDisplayOutputSurface::~SurfaceDisplayOutputSurface() {
   client_ = NULL;
   if (!surface_id_.is_null()) {
     factory_.Destroy(surface_id_);
   }
 }
 
 void SurfaceDisplayOutputSurface::ReceivedVSyncParameters(
@@ skipping 30 matching lines @@
 bool SurfaceDisplayOutputSurface::BindToClient(
     cc::OutputSurfaceClient* client) {
   DCHECK(client);
   DCHECK(display_client_);
   client_ = client;
   // Avoid initializing GL context here, as this should be sharing the
   // Display's context.
   return display_client_->Initialize();
 }
 
+void SurfaceDisplayOutputSurface::ForceReclaimResources() {
+  if (!surface_id_.is_null()) {
+    scoped_ptr<cc::CompositorFrame> frame_copy(new cc::CompositorFrame());

[jamesr, 2015/01/09 01:14:45]

what is this a copy of? this looks more like a completely empty frame

+    frame_copy->delegated_frame_data.reset(new cc::DelegatedFrameData);
+    factory_.SubmitFrame(surface_id_, frame_copy.Pass(),
+                         cc::SurfaceFactory::DrawCallback());
+  }
+}
+
 void SurfaceDisplayOutputSurface::ReturnResources(
     const cc::ReturnedResourceArray& resources) {
   cc::CompositorFrameAck ack;
   ack.resources = resources;
   if (client_)
     client_->ReclaimResources(&ack);
 }
 
 void SurfaceDisplayOutputSurface::SwapBuffersComplete(bool drawn) {
   if (client_)
     client_->DidSwapBuffersComplete();
 }
 
 }  // namespace content