Add histograms that track how long it takes to open the new tab page.

chrome/browser/tab_contents/tab_contents.h

Index: chrome/browser/tab_contents/tab_contents.h
diff --git a/chrome/browser/tab_contents/tab_contents.h b/chrome/browser/tab_contents/tab_contents.h
index 87aeb763c7a428313ba1f170137df76bf8c2e7fc..83613ba44c31ff05d9bf32937f8b533add39e12e 100644
--- a/chrome/browser/tab_contents/tab_contents.h
+++ b/chrome/browser/tab_contents/tab_contents.h
@@ -617,6 +617,16 @@ class TabContents : public PageNavigator,
     opener_dom_ui_type_ = opener_dom_ui_type;
   }
 
+  // We want to time how long it takes to create a new tab page.  This method
+  // gets called as parts of the new tab page have loaded.
+  void LogNewTabTime(const std::string& event_name);
+
+  // Set the time when we started to create the new tab page.  This time is
+  // from before we created this TabContents.
+  void set_new_tab_start_time(const base::TimeTicks& time) {
+    new_tab_start_time_ = time;
+  }
+
  private:
   friend class NavigationController;
   // Used to access the child_windows_ (ConstrainedWindowList) for testing
@@ -1151,6 +1161,9 @@ class TabContents : public PageNavigator,
   // non-NULL and represent the DOMUI of the opening renderer.
   DOMUITypeID opener_dom_ui_type_;
 
+  // The time that we started to create the new tab page.
+  base::TimeTicks new_tab_start_time_;
+
   // ---------------------------------------------------------------------------
 
   DISALLOW_COPY_AND_ASSIGN(TabContents);