Introduce ServiceWorker.MainFramePageLoad.CoreTransition and RedirectChainLength UMAs.

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 83a7d1c616cb49285c447c03d08a9874acef0dca..7b69309cde7c1d67121653f228ee24dabf379f1a 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -58396,6 +58396,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="ServiceWorker.MainFramePageLoad.CoreTransition"
+    enum="ServiceWorkerCoreTransition">
+  <owner>horo@chromium.org</owner>
+  <summary>
+    The transition type for main frame page loads controlled by a service
+    worker.
+  </summary>
+</histogram>
+
+<histogram name="ServiceWorker.MainFramePageLoad.RedirectChainLength"
+    units="urls">
+  <owner>horo@chromium.org</owner>
+  <summary>
+    Total length of the server redirects during main frame page loads controlled
+    by a service worker.
+  </summary>
+</histogram>
+
 <histogram name="ServiceWorker.MessageEvent.Time" units="ms">
   <obsolete>
     Deprecated 2016-04 in favor of ServiceWorker.ExtendableMessageEvent.Time.
@@ -101160,6 +101178,20 @@ value.
   <int value="5" label="OpaqueRedirect"/>
 </enum>
 
+<enum name="ServiceWorkerCoreTransition" type="int">

[falken, 2016/12/06 01:25:14]

Since these come from ui::PageTransition, could these possibly just be called
PageTransition. Since there's already a deprecated
PrerenderLocalVisitCoreTransition could we just reuse/rename that?

[horo, 2016/12/06 01:44:51]

Done.

+  <int value="0" label="LINK"/>

[falken, 2016/12/06 01:25:14]

Add a <summary> field with a pointer to the corresponding enum in .h file?

[horo, 2016/12/06 01:44:51]

Done.

[horo, 2016/12/06 01:44:51]

Done.

+  <int value="1" label="TYPED"/>
+  <int value="2" label="AUTO_BOOKMARK"/>
+  <int value="3" label="AUTO_SUBFRAME"/>
+  <int value="4" label="MANUAL_SUBFRAME"/>
+  <int value="5" label="GENERATED"/>
+  <int value="6" label="START_PAGE"/>
+  <int value="7" label="FORM_SUBMIT"/>
+  <int value="8" label="RELOAD"/>
+  <int value="9" label="KEYWORD"/>
+  <int value="10" label="GENERATED"/>

[falken, 2016/12/06 01:25:14]

5 and 10 are both GENERATED

[horo, 2016/12/06 01:44:51]

Done.

+</enum>
+
 <enum name="ServiceWorkerDatabaseStatus" type="int">
   <int value="0" label="OK"/>
   <int value="1" label="Not Found Error"/>