cc: Add historgram for the number of render passes in an ubercomp delegated frame.

content/common/cc_messages.cc

Index: content/common/cc_messages.cc
diff --git a/content/common/cc_messages.cc b/content/common/cc_messages.cc
index bcdf0f0f2252c1a4f93e2ce347cbba3645980435..845b4c9dc483593c9211f07cff169f16df307817 100644
--- a/content/common/cc_messages.cc
+++ b/content/common/cc_messages.cc
@@ -4,6 +4,7 @@
 
 #include "content/common/cc_messages.h"
 
+#include "base/metrics/histogram.h"
 #include "cc/compositor_frame.h"
 #include "content/public/common/common_param_traits.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebData.h"
@@ -596,6 +597,7 @@ void ParamTraits<cc::Mailbox>::Log(const param_type& p, std::string* l) {
 }
 
 void ParamTraits<cc::CompositorFrame>::Write(Message* m, const param_type& p) {
+  HISTOGRAM_COUNTS("Renderer4.renderPassCount", frame.renderPasses.size());

[piman, 2012/12/03 20:30:22]

I was thinking of adding this in the GLRenderer (or DirectRenderer), so that we
can get data now.

[danakj, 2012/12/03 20:31:41]

Oh, I thought that too, then I realized we get more renderpasses for aura
browser UI than we get for web pages. But I guess for the values we're concerned
about aura won't be hitting them?

   WriteParam(m, p.size);
   WriteParam(m, p.resource_list);
   WriteParam(m, p.render_pass_list.size());