Issue trace events to gather repaint information.

Source/core/frame/FrameView.cpp

Index: Source/core/frame/FrameView.cpp
diff --git a/Source/core/frame/FrameView.cpp b/Source/core/frame/FrameView.cpp
index 95f79cbc724c033eeb430f97c5e0db39788b65c4..fd2a155b01686f09bd18c10661faba55826f3193 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -1033,6 +1033,8 @@ void FrameView::repaintTree(RenderObject* root)
     // we continue to track repaint rects until this function is called.
     ASSERT(!m_nestedLayoutCount);
 
+    TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("blink.repaint"), "FrameView::repaintTree");
+
     // FIXME: really, we're in the repaint phase here, and the compositing queries are legal.
     // Until those states are fully fledged, I'll just disable the ASSERTS.
     DisableCompositingQueryAsserts disabler;