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

This doesn't time all loads of the new tab page, just new foreground
tabs using ctrl+t or the plus button.  This includes the time it takes
to create the tab contents and logs the time until JS has started
executing, domcontentloaded, and onload.

Note: onload doesn't mean the page is done loading.  We have "NewTabUI load" for that.

BUG=23120

Review URL: http://codereview.chromium.org/242107

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@27918 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 8 insertions, 2 deletions

diff --git a/chrome/browser/browser.cc b/chrome/browser/browser.cc
index e0cc047..1223101 100644
--- a/chrome/browser/browser.cc
+++ b/chrome/browser/browser.cc
@@ -1512,8 +1512,14 @@ TabContents* Browser::AddBlankTab(bool foreground) {
 }
 
 TabContents* Browser::AddBlankTabAt(int index, bool foreground) {
-  return AddTabWithURL(GURL(chrome::kChromeUINewTabURL), GURL(),
-                       PageTransition::TYPED, foreground, index, false, NULL);
+  // Time new tab page creation time.  We keep track of the timing data in
+  // TabContents, but we want to include the time it takes to create the
+  // TabContents object too.
+  base::TimeTicks new_tab_start_time = base::TimeTicks::Now();
+  TabContents* tab_contents =  AddTabWithURL(GURL(chrome::kChromeUINewTabURL),
+      GURL(), PageTransition::TYPED, foreground, index, false, NULL);
+  tab_contents->set_new_tab_start_time(new_tab_start_time);
+  return tab_contents;
 }
 
 Browser* Browser::CreateNewStripWithContents(TabContents* detached_contents,