Add some basic success/failure UMA logging for autofill.

chrome/browser/autofill/autofill_download.h

Index: chrome/browser/autofill/autofill_download.h
diff --git a/chrome/browser/autofill/autofill_download.h b/chrome/browser/autofill/autofill_download.h
index 5987c9dcacede6a2c450e781fe5bccb969691c59..488c3b3c632d506cd469e7deb87c5543611da34c 100644
--- a/chrome/browser/autofill/autofill_download.h
+++ b/chrome/browser/autofill/autofill_download.h
@@ -16,6 +16,7 @@
 #include "chrome/browser/autofill/form_structure.h"
 #include "chrome/common/net/url_fetcher.h"
 
+class AutoFillMetrics;
 class Profile;
 
 // Handles getting and updating AutoFill heuristics.
@@ -60,7 +61,8 @@ class AutoFillDownloadManager : public URLFetcher::Delegate {
   // Starts a query request to AutoFill servers. The observer is called with the
   // list of the fields of all requested forms.
   // |forms| - array of forms aggregated in this request.
-  bool StartQueryRequest(const ScopedVector<FormStructure>& forms);
+  bool StartQueryRequest(const ScopedVector<FormStructure>& forms,
+                         const AutoFillMetrics& metric_logger);
 
   // Start upload request if necessary. The probability of request going
   // over the wire are GetPositiveUploadRate() if it was matched by