[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..9ccee4cb38882ca1483126b4e98fa5731bebf773 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(ManifestUmaUtil::FETCH_EMPTY_URL);
     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(ManifestUmaUtil::FETCH_UNSPECIFIED_REASON);

[Miguel Garcia, 2014/10/02 15:56:42]

This can happen if fetching the url throws a 500 I assume. So we do know
something about the reason?

[mlamouri (slow - plz ping), 2014/10/02 16:10:55]

We knows the http error code but I don't think we should worry about that for
the moment.

     ResolveCallbacks(ResolveStateFailure);
     return;
   }
 
+  ManifestUmaUtil::FetchSucceeded();
   manifest_ = ManifestParser::Parse(data, response.url(), document_url);
 
   fetcher_.reset();