<webview> Implement clear http cache API.

extensions/browser/guest_view/web_view/web_view_guest.h

Index: extensions/browser/guest_view/web_view/web_view_guest.h
diff --git a/extensions/browser/guest_view/web_view/web_view_guest.h b/extensions/browser/guest_view/web_view/web_view_guest.h
index 88bfac2a48af6dc47e3bdad40595144bfbdb6aa2..6bd29214b69b79f5f596296edb769018017c782a 100644
--- a/extensions/browser/guest_view/web_view/web_view_guest.h
+++ b/extensions/browser/guest_view/web_view/web_view_guest.h
@@ -243,6 +243,12 @@ class WebViewGuest : public GuestView<WebViewGuest>,
 
   ScriptExecutor* script_executor() { return script_executor_.get(); }
 
+  scoped_ptr<WebViewGuestDelegate> SetDelegateForTesting(
+      scoped_ptr<WebViewGuestDelegate> delegate) {
+    web_view_guest_delegate_.swap(delegate);
+    return delegate.Pass();
+  }
+
  private:
   friend class WebViewPermissionHelper;
 
@@ -252,6 +258,10 @@ class WebViewGuest : public GuestView<WebViewGuest>,
 
   void AttachWebViewHelpers(content::WebContents* contents);
 
+  void ClearDataInternal(const base::Time remove_since,
+                         uint32 removal_mask,
+                         const base::Closure& callback);
+
   void OnWebViewNewWindowResponse(int new_window_instance_id,
                                   bool allow,
                                   const std::string& user_input);