Log NTP launch time until user can do a search.

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 b67c2b49be90fcdf21103032acfb2e0f6c854ad7..70a34ac38bddae81f38961c9f2980d7c267ed9b7 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -38350,6 +38350,16 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="NewTabPage.LoadType" enum="NTPLoadType">
+  <owner>mvanouwerkerk@chromium.org</owner>
+  <summary>
+    Android: the type of load for the NTP, such as cold or warm start. It's a
+    warm start if the native library is already loaded and initialized at the

[Alexei Svitkine (slow), 2016/12/07 16:36:05]

Nit: Suggest copying this extra description to the other histograms you're
adding. Or alternatively reference this histogram from their descriptions for
details.

[Michael van Ouwerkerk, 2016/12/07 17:15:50]

Done.

+    time the activity is created. This might happen if for example a service was
+    already running.
+  </summary>
+</histogram>
+
 <histogram name="NewTabPage.LogoClick" enum="NewTabPageLogoClick">
   <owner>ianwen@chromium.org</owner>
   <summary>
@@ -38695,6 +38705,22 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="NewTabPage.SearchAvailableLoadTime.ColdStart" units="ms">
+  <owner>mvanouwerkerk@chromium.org</owner>
+  <summary>
+    Android: the time until the search box became available on the NTP in a cold
+    start.
+  </summary>
+</histogram>
+
+<histogram name="NewTabPage.SearchAvailableLoadTime.WarmStart" units="ms">
+  <owner>mvanouwerkerk@chromium.org</owner>
+  <summary>
+    Android: the time until the search box became available on the NTP in a warm
+    start.
+  </summary>
+</histogram>
+
 <histogram name="NewTabPage.SearchURLs.Total">
   <obsolete>
     Deprecated 2016-02 (and not recorded for some time before that).
@@ -95908,6 +95934,12 @@ value.
   <int value="4" label="Fits with field trial"/>
 </enum>
 
+<enum name="NTPLoadType" type="int">
+  <int value="0" label="Cold startup"/>
+  <int value="1" label="Warm startup"/>
+  <int value="2" label="Other, not at startup"/>
+</enum>
+
 <enum name="NtpMostVisitedScheme" type="int">
   <obsolete>
     Deprecated 2016-05.