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 002f32c4ab21a854ea6fea6602830842d28940aa..eb885801caa6d1724d10c1fbba66e0e8744ddbf5 100644
--- a/cc/output/gl_renderer.cc
+++ b/cc/output/gl_renderer.cc
@@ -2892,7 +2892,7 @@ 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");
@@ -2900,8 +2900,6 @@ 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