Adds a new UMA histogram to measure the NTP load time since navigation

chrome/renderer/searchbox/searchbox.cc

Index: chrome/renderer/searchbox/searchbox.cc
diff --git a/chrome/renderer/searchbox/searchbox.cc b/chrome/renderer/searchbox/searchbox.cc
index d1d71a7ffd9d0d0589fe1d66a6b05e7a81512b77..ca4b28718e61f4a81a9508efd25f3f68e61aa04c 100644
--- a/chrome/renderer/searchbox/searchbox.cc
+++ b/chrome/renderer/searchbox/searchbox.cc
@@ -161,13 +161,10 @@ SearchBox::~SearchBox() {
 
 void SearchBox::LogEvent(NTPLoggingEventType event) {
   // navigation_start in ms.
-  uint64 start = 1000 *
-                 render_view()
-                     ->GetMainRenderFrame()
-                     ->GetWebFrame()
-                     ->performance()

[kmadhusu, 2015/03/17 00:06:29]

Did you rebase this CL against crrev.com/1006753003? Is this change intentional?

[fserb, 2015/03/17 16:02:17]

yeah. It is on top of the other.
I must have forgotten to "cl upload <base>". Just fixed that.
I can only submit this after the 1006753003. I decided to split them to make
them a bit simpler. But not sure if there's a better way to tell codereview
about that.

-                     .navigationStart();
-  uint64 now = (base::Time::Now() - base::Time::UnixEpoch()).InMilliseconds();
+  uint64 start = 1000 * (render_view()->GetMainRenderFrame()->
+                             GetWebFrame()->performance().navigationStart());
+  uint64 now =
+      (base::TimeTicks::Now() - base::TimeTicks::UnixEpoch()).InMilliseconds();
   DCHECK(now >= start);
   uint64 delta = now - start;
   DVLOG(1) << now << " - " << start << " = " << delta;