Perf metric tracking the wallclock time it takes to show a new tab page.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 9c8710c1e12704589b4ab52ca22379fdf2014244..f564bd4f56e6487938359db993cb32a87b9aa0ec 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -75905,6 +75905,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Toolbar.Menu.NewIncognitoTabPresentationDuration" units="ms">
+  <owner>peterlaurens@chromium.org</owner>
+  <summary>
+    The number of millseconds between the user requesting a new incognito tab,
+    e.g. by tapping the New Incognito Tab entry in the main tools menu, and it

[Ilya Sherman, 2017/05/23 22:55:23]

Should "e.g. " be "i.e." for all of these histograms, or are there alternate UI
flows as well?

[PL, 2017/06/08 17:57:47]

There are other flows - for example the plus button will also create a new tab
and be tracked by this metric. There might also be other ways in the future.

+    completing its animation on screen.
+  </summary>
+</histogram>
+
+<histogram name="Toolbar.Menu.NewTabPresentationDuration" units="ms">
+  <owner>peterlaurens@chromium.org</owner>
+  <summary>
+    The number of millseconds between the user requesting a new tab, e.g. by
+    tapping the New Tab entry in the main tools menu, and it completing its
+    animation on screen.
+  </summary>
+</histogram>
+
 <histogram name="Toolbar.ShowToolsMenuResponsiveness" units="ms">
   <owner>peterlaurens@chromium.org</owner>
   <summary>
@@ -75915,6 +75933,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Toolbar.TabSwitcher.NewIncognitoTabPresentationDuration" units="ms">
+  <owner>peterlaurens@chromium.org</owner>
+  <summary>
+    The number of millseconds between the user requesting a new incognito tab,
+    from within the tab switcher, e.g. by tapping the New Tab button from
+    the tab switcher UI, and it completing its animation on screen.
+  </summary>
+</histogram>
+
+<histogram name="Toolbar.TabSwitcher.NewTabPresentationDuration" units="ms">
+  <owner>peterlaurens@chromium.org</owner>
+  <summary>
+    The number of millseconds between the user requesting a new tab, from  
+    within the tab switcher UI, e.g. by tapping the New Tab button from
+    the tab switcher UI, and it completing its animation on screen.
+  </summary>
+</histogram>
+
 <histogram name="TopSites.NumberOfApplyBlacklist">
   <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
   <summary>The number of times TopSitesImpl::ApplyBlacklist is called.</summary>