Adds UMA for PrerenderingOffliner request processing result status.

components/offline_pages/background/request_coordinator.cc

Index: components/offline_pages/background/request_coordinator.cc
diff --git a/components/offline_pages/background/request_coordinator.cc b/components/offline_pages/background/request_coordinator.cc
index 6292aa8cc7b24ddb6fc7fe430d8529531f288589..d5f1081fdb8bdaef03986e828911a138999bb52d 100644
--- a/components/offline_pages/background/request_coordinator.cc
+++ b/components/offline_pages/background/request_coordinator.cc
@@ -9,6 +9,7 @@
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/logging.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/time/time.h"
 #include "components/offline_pages/background/offliner_factory.h"
 #include "components/offline_pages/background/offliner_policy.h"
@@ -19,6 +20,15 @@
 namespace offline_pages {
 
 namespace {
+
+// Records the final request status UMA for an offlining request. This should
+// only be called once per Offliner::LoadAndSave request.
+void RecordOfflinerResultUMA(Offliner::RequestStatus request_status) {
+  UMA_HISTOGRAM_ENUMERATION("OfflinePages.Background.OfflinerRequestStatus",
+                            request_status,
+                            Offliner::RequestStatus::STATUS_COUNT);
+}
+
 // TODO(dougarnett/petewil): Move to Policy object. Also consider lower minimum
 // battery percentage once there is some processing time limits in place.
 const Scheduler::TriggerConditions kUserRequestTriggerConditions(
@@ -89,8 +99,11 @@ void RequestCoordinator::UpdateRequestCallback(
 
 void RequestCoordinator::StopProcessing() {
   is_canceled_ = true;
-  if (offliner_ && is_busy_)
+  if (offliner_ && is_busy_) {
     offliner_->Cancel();
+    RecordOfflinerResultUMA(
+        Offliner::RequestStatus::REQUEST_COORDINATOR_CANCELED);
+  }
 
   // Let the scheduler know we are done processing.
   scheduler_callback_.Run(true);
@@ -171,6 +184,7 @@ void RequestCoordinator::OfflinerDoneCallback(const SavePageRequest& request,
       request.client_id().name_space,
       "Saved",
       request.request_id());
+  RecordOfflinerResultUMA(status);
   last_offlining_status_ = status;
   watchdog_timer_.Stop();