ServiceWorker: Add UMA for ServiceWorkerDiskCache

content/browser/service_worker/service_worker_write_to_cache_job.cc

Index: content/browser/service_worker/service_worker_write_to_cache_job.cc
diff --git a/content/browser/service_worker/service_worker_write_to_cache_job.cc b/content/browser/service_worker/service_worker_write_to_cache_job.cc
index 313e3a4796682e69c0c605d30d3ee13fd4c94363..bd16a132004e8d3321646c75536d9b0a09fdfaf3 100644
--- a/content/browser/service_worker/service_worker_write_to_cache_job.cc
+++ b/content/browser/service_worker/service_worker_write_to_cache_job.cc
@@ -6,6 +6,7 @@
 
 #include "content/browser/service_worker/service_worker_context_core.h"
 #include "content/browser/service_worker/service_worker_disk_cache.h"
+#include "content/browser/service_worker/service_worker_histograms.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
 #include "net/http/http_request_headers.h"
@@ -191,6 +192,8 @@ void ServiceWorkerWriteToCacheJob::WriteHeadersToCache() {
 void ServiceWorkerWriteToCacheJob::OnWriteHeadersComplete(int result) {
   SetStatus(net::URLRequestStatus());  // Clear the IO_PENDING status
   if (result < 0) {
+    ServiceWorkerHistograms::CountWriteResponseResult(
+        ServiceWorkerHistograms::WRITE_HEADERS_ERROR);
     AsyncNotifyDoneHelper(net::URLRequestStatus(
         net::URLRequestStatus::FAILED, result));
     return;
@@ -218,10 +221,14 @@ void ServiceWorkerWriteToCacheJob::OnWriteDataComplete(int result) {
     return;
   }
   if (result < 0) {
+    ServiceWorkerHistograms::CountWriteResponseResult(
+        ServiceWorkerHistograms::WRITE_DATA_ERROR);
     AsyncNotifyDoneHelper(net::URLRequestStatus(
         net::URLRequestStatus::FAILED, result));
     return;
   }
+  ServiceWorkerHistograms::CountWriteResponseResult(
+      ServiceWorkerHistograms::WRITE_OK);
   SetStatus(net::URLRequestStatus());  // Clear the IO_PENDING status
   NotifyReadComplete(result);
 }