Add tracing for RenderView::hitTest and FrameView::invalidateTree.

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 0a043b360750f4097852dc8cbf5a87af31cbe8e0..b3fb1799843a88d0e437f310fd8241c459d9d719 100644
--- a/Source/core/frame/FrameView.cpp
+++ b/Source/core/frame/FrameView.cpp
@@ -1036,6 +1036,8 @@ void FrameView::layout(bool allowSubtree)
 // See http://crbug.com/306706
 void FrameView::invalidateTree(RenderObject* root)
 {
+    TRACE_EVENT0("blink", "FrameView::invalidateTree");

[dsinclair, 2014/06/06 01:59:03]

This already exists on line 1047.

[chrishtr, 2014/06/06 02:08:03]

Done.

[ojan, 2014/06/06 03:22:38]

Why is the one on line 1047 disabled by default?

[dsinclair, 2014/06/06 03:29:27]

The TRACE_STR_COPY has a cost which I didn't want to incur in the default case.

[ojan, 2014/06/06 05:53:11]

Can we put in a trace (instead or in addition the the one below) that is enabled
by default that doesn't add the root parameter? Having the trace by default is
more useful than having the trace with the extra information. When we were
looking at the trace today, there was this untraced block and we had to stare at
the code and add speculative traces to see where the time was going.

+
     ASSERT(RuntimeEnabledFeatures::repaintAfterLayoutEnabled());
     ASSERT(!root->needsLayout());
     // We should only invalidate paints for the outer most layout. This works as