[Most Visited] Log suggestion provider to UMA

chrome/browser/search/most_visited_iframe_source.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_SEARCH_MOST_VISITED_IFRAME_SOURCE_H_
 #define CHROME_BROWSER_SEARCH_MOST_VISITED_IFRAME_SOURCE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "base/gtest_prod_util.h"
 #include "chrome/browser/search/iframe_source.h"
 
 // Serves HTML for displaying suggestions using iframes, e.g.
 // chrome-search://suggestion/loader.html
 class MostVisitedIframeSource : public IframeSource {
  public:
   MostVisitedIframeSource();
   virtual ~MostVisitedIframeSource();
 
   // Number of Most Visited elements on the NTP for logging purposes.
   static const int kNumMostVisited;
   // Name of the histogram keeping track of Most Visited clicks.
   static const char kMostVisitedHistogramName[];
 
   // Overridden from IframeSource. Public for testing.
   virtual void StartDataRequest(
       const std::string& path_and_query,
       int render_process_id,
       int render_view_id,
       const content::URLDataSource::GotDataCallback& callback) OVERRIDE;
 
  protected:
   // Overridden from IframeSource:
   virtual std::string GetSource() const OVERRIDE;
 
   virtual bool ServesPath(const std::string& path) const OVERRIDE;
 
+ private:
+  FRIEND_TEST_ALL_PREFIXES(MostVisitedIframeSourceTest,
+                           LogEndpointIsValidWithProvider);
+
+  // Logs the click on a Most Visited tile for a specific |provider|. Note that
+  // the UMA_HISTOGRAM_ENUMERATION macro cannot be used since it caches the
+  // histogram object at the call site, which will not work in this case.
+  void LogMostVisitedProviderClick(int position, const std::string& provider);
+
+  // Returns the name of the histogram that should be logged for a click to a
+  // specified Most Visited |provider|.
+  static std::string GetHistogramNameForProvider(const std::string& provider);
+
   DISALLOW_COPY_AND_ASSIGN(MostVisitedIframeSource);
 };
 
 #endif  // CHROME_BROWSER_SEARCH_MOST_VISITED_IFRAME_SOURCE_H_