Add UMA metrics for blocked plugins.

chrome/browser/content_settings/tab_specific_content_settings.h

Index: chrome/browser/content_settings/tab_specific_content_settings.h
diff --git a/chrome/browser/content_settings/tab_specific_content_settings.h b/chrome/browser/content_settings/tab_specific_content_settings.h
index 448844d699aafeed5e776a69ff329dffa24936d9..dd9d2adb17077d4a997e7e51af3b370652ca26d3 100644
--- a/chrome/browser/content_settings/tab_specific_content_settings.h
+++ b/chrome/browser/content_settings/tab_specific_content_settings.h
@@ -169,7 +169,8 @@ class TabSpecificContentSettings : public TabContentsObserver,
 
   // Message handlers. Public for testing.
   void OnContentBlocked(ContentSettingsType type,
-                        const std::string& resource_identifier);
+                        const std::string& resource_identifier,
+                        ContentSetting setting);
   void OnAppCacheAccessed(const GURL& manifest_url, bool blocked_by_policy);
 
   // These methods are invoked on the UI thread by the static functions above.