OnDrawHardware() implementation with async messages

content/browser/android/synchronous_compositor_host.cc

Index: content/browser/android/synchronous_compositor_host.cc
diff --git a/content/browser/android/synchronous_compositor_host.cc b/content/browser/android/synchronous_compositor_host.cc
index b0e0b9dab5a7012e3af9754467aba79c169f46ee..e8fecd035a62ac56742afa6f4f070c233cacbe35 100644
--- a/content/browser/android/synchronous_compositor_host.cc
+++ b/content/browser/android/synchronous_compositor_host.cc
@@ -88,6 +88,7 @@ bool SynchronousCompositorHost::OnMessageReceived(const IPC::Message& message) {
     IPC_MESSAGE_HANDLER(SyncCompositorHostMsg_OutputSurfaceCreated,
                         OutputSurfaceCreated)
     IPC_MESSAGE_HANDLER(SyncCompositorHostMsg_UpdateState, ProcessCommonParams)
+    IPC_MESSAGE_HANDLER(CompositorHostMsg_Frame, ReceiveFrame)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled;
@@ -106,20 +107,46 @@ SynchronousCompositor::Frame SynchronousCompositorHost::DemandDrawHw(
   SynchronousCompositor::Frame frame;
   frame.frame.reset(new cc::CompositorFrame);
   SyncCompositorCommonRendererParams common_renderer_params;
-  if (!sender_->Send(new SyncCompositorMsg_DemandDrawHw(
-          routing_id_, params, &common_renderer_params,
-          &frame.output_surface_id, frame.frame.get()))) {
-    return SynchronousCompositor::Frame();
-  }
-  ProcessCommonParams(common_renderer_params);
-  if (!frame.frame->delegated_frame_data) {
-    // This can happen if compositor did not swap in this draw.
-    frame.frame.reset();
-  }
-  if (frame.frame) {
-    UpdateFrameMetaData(frame.frame->metadata.Clone());
-  }
-  return frame;
+
+  /* Send an async message instead of a synchronous one.
+   * Currently not sure what to do in the analogous case
+   * when sending sync message returns false. */
+  //  if (!sender_->Send(new SyncCompositorMsg_DemandDrawHw(
+  //          routing_id_, params, &common_renderer_params,
+  //          &frame.output_surface_id, frame.frame.get()))) {
+  //    return SynchronousCompositor::Frame();
+  //  }
+
+  sender_->Send(new CompositorMsg_DemandDrawHw(routing_id_, params));
+  /* Now that the sent message is async, the following processing
+   * of the result has to be done upon receiving the reply. */
+
+  //  ProcessCommonParams(common_renderer_params);
+  //  if (!frame.frame->delegated_frame_data) {
+  //    // This can happen if compositor did not swap in this draw.
+  //    frame.frame.reset();
+  //  }
+  //  if (frame.frame) {
+  //    UpdateFrameMetaData(frame.frame->metadata.Clone());
+  //  }
+  //  return frame;
+  //
+  return nullptr;
+}
+
+void SynchronousCompositorHost::ReceiveFrame(
+    content::SyncCompositorCommonRendererParams params,
+    uint32_t output_surface_id,
+    cc::CompositorFrame) {
+  // TODO: the return message is received in this class, but
+  //  the received frame should be processed in BVR class (should it?)
+  //  because other data is stored there (e.g. current frame consumer)
+  //
+  //  Either:
+  //  1. pass the received frame back to browser view renderer (is it
+  //      appropriate?)
+  //  or
+  //  2. pass the necessary things from bvr to here
 }
 
 void SynchronousCompositorHost::UpdateFrameMetaData(