cc: Introduce BeginFrame sequence numbers and acknowledgements.

cc/output/gl_renderer.cc

Index: cc/output/gl_renderer.cc
diff --git a/cc/output/gl_renderer.cc b/cc/output/gl_renderer.cc
index 71861fb361d8b7dac8789e2fa311af09b4f014d7..687de6ddf500a6d8aa83bfdd968747c8ec963ab4 100644
--- a/cc/output/gl_renderer.cc
+++ b/cc/output/gl_renderer.cc
@@ -2894,7 +2894,7 @@ void GLRenderer::DrawQuadGeometry(const gfx::Transform& projection_matrix,
   gl_->DrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, 0);
 }
 
-void GLRenderer::SwapBuffers(std::vector<ui::LatencyInfo> latency_info) {
+void GLRenderer::SwapBuffers(OutputSurfaceFrame output_frame) {
   DCHECK(visible_);
 
   TRACE_EVENT0("cc", "GLRenderer::SwapBuffers");
@@ -2902,8 +2902,6 @@ void GLRenderer::SwapBuffers(std::vector<ui::LatencyInfo> latency_info) {
 
   gfx::Size surface_size = surface_size_for_swap_buffers();
 
-  OutputSurfaceFrame output_frame;
-  output_frame.latency_info = std::move(latency_info);
   output_frame.size = surface_size;
   if (use_partial_swap_) {
     // If supported, we can save significant bandwidth by only swapping the