Plugin Power Saver: Add missing RenderFrame null-checks in placeholders

chrome/renderer/plugins/chrome_plugin_placeholder.cc

Index: chrome/renderer/plugins/chrome_plugin_placeholder.cc
diff --git a/chrome/renderer/plugins/chrome_plugin_placeholder.cc b/chrome/renderer/plugins/chrome_plugin_placeholder.cc
index 028a70bfda852f87fee99f427febca3de7fe070e..e6d97d705f80495e875b87a3c187bae2e930a84f 100644
--- a/chrome/renderer/plugins/chrome_plugin_placeholder.cc
+++ b/chrome/renderer/plugins/chrome_plugin_placeholder.cc
@@ -289,6 +289,8 @@ void ChromePluginPlaceholder::ShowContextMenu(
     const blink::WebMouseEvent& event) {
   if (context_menu_request_id_)
     return;  // Don't allow nested context menu requests.
+  if (!render_frame())
+    return;
 
   content::ContextMenuParams params;
 
@@ -361,6 +363,7 @@ blink::WebPlugin* ChromePluginPlaceholder::CreatePlugin() {
 }
 
 void ChromePluginPlaceholder::OnBlockedTinyContent() {
+  DCHECK(render_frame());
   if (did_send_blocked_content_notification_)
     return;