[Offline Pages] Adds UMA for result of attempts to immediately start background loading.

components/offline_pages/background/request_coordinator.h

Index: components/offline_pages/background/request_coordinator.h
diff --git a/components/offline_pages/background/request_coordinator.h b/components/offline_pages/background/request_coordinator.h
index 537e5a85df475cd6b747f28e5facdab6ca6170a1..31eee68fce0debea855d1695edcb813210f76e1a 100644
--- a/components/offline_pages/background/request_coordinator.h
+++ b/components/offline_pages/background/request_coordinator.h
@@ -169,6 +169,24 @@ class RequestCoordinator : public KeyedService,
   }
 
  private:
+  enum OfflinerImmediateStartStatus {

[Mark P, 2016/10/06 23:11:36]

Can you please add the warning at the top as well?

[dougarnett, 2016/10/07 00:18:56]

Done.

[Mark P, 2016/10/07 04:44:06]

Next time you update this file, can you please update the warning, following the
guideline here:
https://chromium.googlesource.com/chromium/src.git/+/HEAD/tools/metrics/histo...

In particular, your warning misses the information that values shouldn't be
changed or reused.  You just state that they need to stay in sync with
histograms.xml.

+    // Did start processing request.
+    STARTED = 0,
+    // Already busy processing a request.
+    BUSY = 1,
+    // The Offliner did not accept processing the request.
+    NOT_ACCEPTED = 2,
+    // No current network connection.
+    NO_CONNECTION = 3,
+    // Weak network connection (worse than 2G speed)
+    // according to network quality estimator.
+    WEAK_CONNECTION = 4,
+    // Did not start because this is svelte device.
+    NOT_STARTED_ON_SVELTE = 5,
+    // NOTE: insert new values above this line and update histogram enum too.
+    STATUS_COUNT = 6,
+  };
+
   // Receives the results of a get from the request queue, and turns that into
   // SavePageRequest objects for the caller of GetQueuedRequests.
   void GetQueuedRequestsCallback(
@@ -205,6 +223,8 @@ class RequestCoordinator : public KeyedService,
   // as to other device conditions).
   void StartProcessingIfConnected();
 
+  OfflinerImmediateStartStatus TryImmediateStart();
+
   // Check the request queue, and schedule a task corresponding
   // to the least restrictive type of request in the queue.
   void ScheduleAsNeeded();