Implement about:tracing UI for the sampling profiler (Chromium part)

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index be7973e3b638aaf586c384c8df41b6422af5db73..12b5e9104bf1f00208521aa990570ff2632ff66b 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -2120,8 +2120,11 @@ void RenderViewImpl::UpdateTitle(WebFrame* frame,
   if (frame->parent())
     return;
 
+  std::string title_suffix =
+      GetVisibilityState() == WebKit::WebPageVisibilityStatePrerender ?
+      " (Prerender)" : "";
   base::debug::TraceLog::GetInstance()->UpdateProcessLabel(
-      routing_id_, UTF16ToUTF8(title));
+      routing_id_, UTF16ToUTF8(title) + title_suffix);
 
   string16 shortened_title = title.substr(0, kMaxTitleChars);
   Send(new ViewHostMsg_UpdateTitle(routing_id_, page_id_, shortened_title,