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

chrome/browser/guestview/webview/plugin_permission_helper.cc

Index: chrome/browser/guestview/webview/plugin_permission_helper.cc
diff --git a/chrome/browser/guestview/webview/plugin_permission_helper.cc b/chrome/browser/guestview/webview/plugin_permission_helper.cc
index d223dbdcdf140318ee2d345685e5c5ec3f0a6fd9..11c3f7367258569127b79c18d0bac1cd36408dfd 100644
--- a/chrome/browser/guestview/webview/plugin_permission_helper.cc
+++ b/chrome/browser/guestview/webview/plugin_permission_helper.cc
@@ -100,7 +100,8 @@ void PluginPermissionHelper::OnRemovePluginPlaceholderHost(int placeholder_id) {
 
 void PluginPermissionHelper::OnPermissionResponse(const std::string& identifier,
                                                   bool allow,
-                                                  const std::string& input) {
+                                                  const std::string& input,
+                                                  bool user_initiated) {
   if (allow) {
     RenderViewHost* host = web_contents()->GetRenderViewHost();
     ChromePluginServiceFilter::GetInstance()->AuthorizeAllPlugins(
@@ -109,6 +110,7 @@ void PluginPermissionHelper::OnPermissionResponse(const std::string& identifier,
         host->GetRoutingID(), identifier));
   }
 
+  // Should we restrict this only for |user_initiated| = true?

[lazyboy, 2013/11/12 18:16:59]

FYI: Pending question. For other permissions, I'm trying to only record
explicitly user initiated allow/deny, to give us a sense if/how the API is being
used.

[Fady Samuel, 2013/11/13 19:29:52]

It's useful to record when plugin requests happen but it's also useful to know
when the user makes an explicit request (Are they actually using the
permissionrequest API?).

[lazyboy, 2013/11/13 19:52:50]

In that case we can record two separate pairs, a pair when user_initiated=true,
and another when user_initiated=false.
WDYT?

re Are they actually using the permissionrequest API?
only in chrome/ layer(WebViewGuest), it's not initiated or handled in content/
layer (BrowserPluginGuest), so there's no *Request class for plugin request like
other ones do (e.g. class BrowserPluginGuest::NewWindowRequest : public
PermissionRequest).

   content::RecordAction(
       allow ? content::UserMetricsAction("WebView.Guest.PluginLoadAllowed") :
               content::UserMetricsAction("WebView.Guest.PluginLoadDenied"));