sync compositor: Add output_surface_id

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 658c818db71bef42528c35f486eafbe4e77ae9de..e9c1631d48525770c5226ad24e9e386a4ea59a1d 100644
--- a/content/browser/android/synchronous_compositor_host.cc
+++ b/content/browser/android/synchronous_compositor_host.cc
@@ -40,6 +40,7 @@ SynchronousCompositorHost::SynchronousCompositorHost(
       use_in_process_zero_copy_software_draw_(use_in_proc_software_draw),
       is_active_(false),
       bytes_limit_(0u),
+      current_output_surface_id_(0u),

[hush (inactive), 2016/03/08 23:55:49]

Not sure where we get the correct value of current_output_surface_id_. Is 0 a
guaranteed invalid id?
Also it is only set during ReturnResources. And we keep using 0u as surface id
in PopulateCommonParams until resources are returned?

We should assign the current_output_surface_id_ during DrawHW at least.

[boliu, 2016/03/09 00:29:59]

Yes
Yeah. The resource list is guaranteed to be empty before the first
ReturnResources. So having an invalid output surface id doesn't really matter.
no! the output_surface_id should refers to the resources that are in the
returned resource array, not what's in the current/new frame

hmm, maybe I should rename this var or add a comment

[hush (inactive), 2016/03/09 02:36:17]

yeah. Renaming the variable name to indicate this would be good.

       root_scroll_offset_updated_by_browser_(false),
       renderer_param_version_(0u),
       need_animate_scroll_(false),
@@ -70,7 +71,7 @@ void SynchronousCompositorHost::DidBecomeCurrent() {
   client_->DidBecomeCurrent(this);
 }
 
-scoped_ptr<cc::CompositorFrame> SynchronousCompositorHost::DemandDrawHw(
+SynchronousCompositor::Frame SynchronousCompositorHost::DemandDrawHw(
     const gfx::Size& surface_size,
     const gfx::Transform& transform,
     const gfx::Rect& viewport,
@@ -80,22 +81,23 @@ scoped_ptr<cc::CompositorFrame> SynchronousCompositorHost::DemandDrawHw(
   SyncCompositorDemandDrawHwParams params(surface_size, transform, viewport,
                                           clip, viewport_rect_for_tile_priority,
                                           transform_for_tile_priority);
-  scoped_ptr<cc::CompositorFrame> frame(new cc::CompositorFrame);
+  SynchronousCompositor::Frame frame;
+  frame.frame.reset(new cc::CompositorFrame);
   SyncCompositorCommonBrowserParams common_browser_params;
   PopulateCommonParams(&common_browser_params);
   SyncCompositorCommonRendererParams common_renderer_params;
   if (!sender_->Send(new SyncCompositorMsg_DemandDrawHw(
           routing_id_, common_browser_params, params, &common_renderer_params,
-          frame.get()))) {
-    return nullptr;
+          &frame.output_surface_id, frame.frame.get()))) {
+    return SynchronousCompositor::Frame();
   }
   ProcessCommonParams(common_renderer_params);
-  if (!frame->delegated_frame_data) {
+  if (!frame.frame->delegated_frame_data) {
     // This can happen if compositor did not swap in this draw.
-    frame.reset();
+    frame.frame.reset();
   }
-  if (frame)
-    UpdateFrameMetaData(frame->metadata);
+  if (frame.frame)
+    UpdateFrameMetaData(frame.frame->metadata);
   return frame;
 }
 
@@ -267,7 +269,12 @@ void SynchronousCompositorHost::SendZeroMemory() {
 }
 
 void SynchronousCompositorHost::ReturnResources(
+    uint32_t output_surface_id,
     const cc::CompositorFrameAck& frame_ack) {
+  if (current_output_surface_id_ != output_surface_id) {
+    returned_resources_.clear();
+    current_output_surface_id_ = output_surface_id;
+  }
   returned_resources_.insert(returned_resources_.end(),
                              frame_ack.resources.begin(),
                              frame_ack.resources.end());
@@ -380,6 +387,7 @@ void SynchronousCompositorHost::PopulateCommonParams(
   DCHECK(params);
   DCHECK(params->ack.resources.empty());
   params->bytes_limit = bytes_limit_;
+  params->output_surface_id = current_output_surface_id_;
   params->ack.resources.swap(returned_resources_);
   if (root_scroll_offset_updated_by_browser_) {
     params->root_scroll_offset = root_scroll_offset_;