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

chrome/renderer/searchbox/searchbox.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/renderer/searchbox/searchbox.h"
 
 #include <string>
 
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
@@ skipping 143 matching lines @@
     most_visited_items_cache_(kMaxInstantMostVisitedItemCacheSize),
     query_(),
     start_margin_(0) {
 }
 
 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;
   render_view()->Send(new ChromeViewHostMsg_LogEvent(
       render_view()->GetRoutingID(), page_seq_no_, event, delta));
 }
 
 void SearchBox::LogMostVisitedImpression(int position,
                                          const base::string16& provider) {
   render_view()->Send(new ChromeViewHostMsg_LogMostVisitedImpression(
@@ skipping 317 matching lines @@
 
 void SearchBox::Reset() {
   query_.clear();
   embedded_search_request_params_ = EmbeddedSearchRequestParams();
   suggestion_ = InstantSuggestion();
   start_margin_ = 0;
   is_focused_ = false;
   is_key_capture_enabled_ = false;
   theme_info_ = ThemeBackgroundInfo();
 }