ServiceWorker: Add UMA for ServiceWorkerDiskCache

content/browser/service_worker/service_worker_read_from_cache_job.cc

Index: content/browser/service_worker/service_worker_read_from_cache_job.cc
diff --git a/content/browser/service_worker/service_worker_read_from_cache_job.cc b/content/browser/service_worker/service_worker_read_from_cache_job.cc
index eddbcd42f82893e19d0e211865e0c4ce3372663e..5189a86c2bde91f19dabc33d6ec5a03161d9e04c 100644
--- a/content/browser/service_worker/service_worker_read_from_cache_job.cc
+++ b/content/browser/service_worker/service_worker_read_from_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"
@@ -134,6 +135,8 @@ void ServiceWorkerReadFromCacheJob::OnReadInfoComplete(int result) {
   scoped_refptr<ServiceWorkerReadFromCacheJob> protect(this);
   if (!http_info_io_buffer_->http_info) {
     DCHECK(result < 0);
+    ServiceWorkerHistograms::CountReadResponseResult(
+        ServiceWorkerHistograms::READ_HEADERS_ERROR);
     NotifyDone(net::URLRequestStatus(net::URLRequestStatus::FAILED, result));
     return;
   }
@@ -170,12 +173,18 @@ void ServiceWorkerReadFromCacheJob::SetupRangeResponse(int resource_size) {
 }
 
 void ServiceWorkerReadFromCacheJob::OnReadComplete(int result) {
-  if (result == 0)
+  ServiceWorkerHistograms::ReadResponseResult check_result;
+  if (result == 0) {
+    check_result = ServiceWorkerHistograms::READ_OK;
     NotifyDone(net::URLRequestStatus());
-  else if (result < 0)
+  } else if (result < 0) {
+    check_result = ServiceWorkerHistograms::READ_DATA_ERROR;
     NotifyDone(net::URLRequestStatus(net::URLRequestStatus::FAILED, result));
-  else
+  } else {
+    check_result = ServiceWorkerHistograms::READ_OK;
     SetStatus(net::URLRequestStatus());  // Clear the IO_PENDING status
+  }
+  ServiceWorkerHistograms::CountReadResponseResult(check_result);
   NotifyReadComplete(result);
 }