Plumb LatencyInfo through aura.

content/browser/renderer_host/render_widget_host_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 
 #include <math.h>
 #include <utility>
 
 #include "base/auto_reset.h"
@@ skipping 2486 matching lines @@
   OnRenderAutoResized(new_size);
 }
 
 void RenderWidgetHostImpl::DetachDelegate() {
   delegate_ = NULL;
 }
 
 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