Make cc::CompositorFrames movable [Part 1 of 2]

cc/output/delegating_renderer.cc

 // Copyright 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 "cc/output/delegating_renderer.h"
 
 #include <set>
 #include <string>
 #include <vector>
 
@@ skipping 81 matching lines @@
   ResourceProvider::ResourceIdArray resources;
   for (const auto& render_pass : out_data.render_pass_list) {
     for (const auto& quad : render_pass->quad_list) {
       for (ResourceId resource_id : quad->resources)
         resources.push_back(resource_id);
     }
   }
   resource_provider_->PrepareSendToParent(resources, &out_data.resource_list);
 }
 
 void DelegatingRenderer::SwapBuffers(const CompositorFrameMetadata& metadata) {

[piman, 2016/06/24 00:56:25]

nit: can we make this take a CompositorFrameMetadata (non-ref), and have the
callers use std::move? Maybe as a follow-up, this patch is getting big, but
LayerTreeHostImpl::SwapBuffers creates the metadata as a temporary, so it seems
worth it.

   TRACE_EVENT0("cc,benchmark", "DelegatingRenderer::SwapBuffers");
   CompositorFrame compositor_frame;
-  compositor_frame.metadata = metadata;
+  compositor_frame.metadata = CompositorFrameMetadata(metadata);
   compositor_frame.delegated_frame_data = std::move(delegated_frame_data_);
-  output_surface_->SwapBuffers(&compositor_frame);
+  output_surface_->SwapBuffers(std::move(compositor_frame));
 }
 
 void DelegatingRenderer::ReceiveSwapBuffersAck(
     const CompositorFrameAck& ack) {
   resource_provider_->ReceiveReturnsFromParent(ack.resources);
 }
 
 void DelegatingRenderer::DidChangeVisibility() {
   ContextProvider* context_provider = output_surface_->context_provider();
   if (!visible()) {
     TRACE_EVENT0("cc", "DelegatingRenderer::SetVisible dropping resources");
     if (context_provider) {
       context_provider->DeleteCachedResources();
       context_provider->ContextGL()->Flush();
     }
   }
   if (context_provider) {
     // If we are not visible, we ask the context to aggressively free resources.
     context_provider->ContextSupport()->SetAggressivelyFreeResources(
         !visible());
   }
 }
 
 }  // namespace cc