Plumb LatencyInfo through aura.

content/browser/renderer_host/render_widget_host_impl.cc

Index: content/browser/renderer_host/render_widget_host_impl.cc
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index 5cb74b81de044e766d43d3eca2a2f7dd5e5c203e..dc4b048235dfaa1642e67fa10047a5263273a88a 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -2504,4 +2504,26 @@ void RenderWidgetHostImpl::DetachDelegate() {
 void RenderWidgetHostImpl::FrameSwapped(const ui::LatencyInfo& latency_info) {
 }
 
+// static
+void RenderWidgetHostImpl::CompositorFrameDrawn(
+    const ui::LatencyInfo& latency_info) {
+  for (ui::LatencyInfo::LatencyMap::const_iterator b =
+           latency_info.latency_components.begin();
+       b != latency_info.latency_components.end();
+       ++b) {
+    if (b->first.first != ui::INPUT_EVENT_LATENCY_COMPONENT)
+      continue;
+    // Matches with GetLatencyComponentId
+    int routing_id = b->first.second & 0xffffffff;
+    int process_id = (b->first.second >> 32) & 0xffffffff;

[piman, 2013/05/31 04:13:44]

I can't say that I'm the biggest fan of this. I guess it works for now but
doesn't seem very scalable to other source of latency. Also, if/when we want to
catch latency at the source (message pump) in the UI layers, we'll need another
set of component ids, that may conflict with this.

Maybe for a later patch, but could we have instead something like a global
registry of things that want notification of the latency info once it flew
through all the system? They could plug in their component ids and avoid having
to encode routing information into it. WDYT?

[jbauman, 2013/05/31 21:51:36]

That's what the LatencyComponentType is for - to prevent conflicts between
different id namespaces.
Yeah, possibly. At least for now I wanted to keep it simple, while there's only
one consumer of these IDs, but later I can imagine it would make sense to have a
global registry.

+    RenderProcessHost* host = RenderProcessHost::FromID(process_id);
+    if (!host)
+      continue;
+    RenderWidgetHost* rwh = host->GetRenderWidgetHostByID(routing_id);
+    if (!rwh)
+      continue;
+    RenderWidgetHostImpl::From(rwh)->FrameSwapped(latency_info);
+  }
+}
+
 }  // namespace content