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

cc/output/delegating_renderer.cc

Index: cc/output/delegating_renderer.cc
diff --git a/cc/output/delegating_renderer.cc b/cc/output/delegating_renderer.cc
index c063c7f608dfbfdbda048ebc7f942af291395b9b..9093a0f0213f554598b5fc1c434f9914a87edc74 100644
--- a/cc/output/delegating_renderer.cc
+++ b/cc/output/delegating_renderer.cc
@@ -102,9 +102,9 @@ void DelegatingRenderer::DrawFrame(RenderPassList* render_passes_in_draw_order,
 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(