Propagate source_frame_number from LTH to DevTools

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index 8fd2a224e87979ce5e96edd3fb10ab799b7cdd54..edc23072871d9936f96ef470ffa4e5781b05f8bb 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -1467,7 +1467,7 @@ void RenderWidget::DoDeferredUpdate() {
 
   // Tracking of frame rate jitter
   base::TimeTicks frame_begin_ticks = gfx::FrameTime::Now();
-  InstrumentWillBeginFrame();
+  InstrumentWillBeginFrame(0);

[jamesr, 2013/11/06 19:04:03]

why zero? we could be in compositing mode at this point

[caseq, 2013/11/07 06:01:45]

We only care about frame ids in the threaded mode, as they're only used to
associate main-thread frames with impl-side frames (and then potentially with
raster/image decode tasks). I can do that if you insist, but that would require
either exposing frame ids from LTH and generating them in another place within
LTH (we only tick source_frame_numbers on impl thread now), or generating them
in RenderWidget (this would also take care of non-composited case), so I'd
rather avoid doing this until we actually need it.

   AnimateIfNeeded();
 
   // Layout may generate more invalidation.  It may also enable the