[Manifest] Add metrics recording.

content/renderer/manifest/manifest_manager.cc

Index: content/renderer/manifest/manifest_manager.cc
diff --git a/content/renderer/manifest/manifest_manager.cc b/content/renderer/manifest/manifest_manager.cc
index d3989e7f42b3d6ac766c40202271b334668144db..18eb7e0ed0826f9e1027fb3eae38bd7203abc00d 100644
--- a/content/renderer/manifest/manifest_manager.cc
+++ b/content/renderer/manifest/manifest_manager.cc
@@ -10,6 +10,7 @@
 #include "content/public/renderer/render_frame.h"
 #include "content/renderer/fetchers/manifest_fetcher.h"
 #include "content/renderer/manifest/manifest_parser.h"
+#include "content/renderer/manifest/manifest_uma_util.h"
 #include "third_party/WebKit/public/platform/WebURLResponse.h"
 #include "third_party/WebKit/public/web/WebDocument.h"
 #include "third_party/WebKit/public/web/WebLocalFrame.h"
@@ -103,6 +104,7 @@ void ManifestManager::FetchManifest() {
   GURL url(render_frame()->GetWebFrame()->document().manifestURL());
 
   if (url.is_empty()) {
+    ManifestUmaUtil::FetchFailed();

[Miguel Garcia, 2014/10/02 14:26:46]

Don't you want to distinguish this case and the one below? It's very different
if the URL does not exist than if we were not able to fetch.

Chance are that we will find more reasons for failure so perhaps it's worth
creating a UMA enum for each error kind and fail with a specific reason.

[mlamouri (slow - plz ping), 2014/10/02 15:35:06]

I've added "empty url" and "unspecified" for the fetch erorr types. We should
improve the granularity if we happen to need it.

     ResolveCallbacks(ResolveStateFailure);
     return;
   }
@@ -122,10 +124,12 @@ void ManifestManager::OnManifestFetchComplete(
     const blink::WebURLResponse& response,
     const std::string& data) {
   if (response.isNull() && data.empty()) {
+    ManifestUmaUtil::FetchFailed();
     ResolveCallbacks(ResolveStateFailure);
     return;
   }
 
+  ManifestUmaUtil::FetchSucceeded();
   manifest_ = ManifestParser::Parse(data, response.url(), document_url);

[Miguel Garcia, 2014/10/02 14:26:46]

don't you want to track when manifest is not parsable?

[mlamouri (slow - plz ping), 2014/10/02 15:35:05]

I've added something. It will be tracked in the parser.

 
   fetcher_.reset();