Add UMA for <webview> APIs: a. ClearData, b. when Permission request is allowed.

content/browser/browser_plugin/browser_plugin_guest.cc

Index: content/browser/browser_plugin/browser_plugin_guest.cc
diff --git a/content/browser/browser_plugin/browser_plugin_guest.cc b/content/browser/browser_plugin/browser_plugin_guest.cc
index 4c01545fab9b8916603142e224ed3dfe5d373dfb..581975eae69f9fbfd6eef78183055d7bbeb2be63 100644
--- a/content/browser/browser_plugin/browser_plugin_guest.cc
+++ b/content/browser/browser_plugin/browser_plugin_guest.cc
@@ -436,7 +436,7 @@ int BrowserPluginGuest::RequestPermission(
                   AsWeakPtr(),
                   request_id);
   // If BrowserPluginGuestDelegate hasn't handled the permission then we simply
-  // reject it immediately.
+  // perform the default action (which is one of allow or reject) immediately.
   if (!delegate_->RequestPermission(
       permission_type, request_info, callback, request->AllowedByDefault())) {
     callback.Run(request->AllowedByDefault(), "");