Plugin Power Saver: Improve Poster behavior for essential plugins.

chrome/browser/plugins/plugin_power_saver_browsertest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/stl_util.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/stringprintf.h"
@@ skipping 367 matching lines @@
 #else
     return true;
 #endif
   }
 };
 
 IN_PROC_BROWSER_TEST_F(PluginPowerSaverBrowserTest, SmallSameOrigin) {
   LoadHTML(
       "<object id='plugin' data='fake.swf' "
       "    type='application/x-ppapi-tests' width='400' height='100'>"
+      "</object>"
+      "<object id='plugin_poster' data='fake.swf' poster='click_me.png' "
+      "    type='application/x-ppapi-tests' width='400' height='100'>"
       "</object>");
   VerifyPluginMarkedEssential(GetActiveWebContents(), "plugin");
+  VerifyPluginMarkedEssential(GetActiveWebContents(), "plugin_poster");
 }
 
 IN_PROC_BROWSER_TEST_F(PluginPowerSaverBrowserTest, SmallCrossOrigin) {
   LoadHTML(
       "<object id='plugin' data='http://otherorigin.com/fake.swf' "
       "    type='application/x-ppapi-tests' width='400' height='100'>"
       "</object>"
       "<br>"
       "<object id='plugin_poster' data='http://otherorigin.com/fake.swf' "
       "    type='application/x-ppapi-tests' width='400' height='100' "
@@ skipping 230 matching lines @@
 
 IN_PROC_BROWSER_TEST_F(PluginPowerSaverBrowserTest, ZoomIndependent) {
   ui_zoom::ZoomController::FromWebContents(GetActiveWebContents())
       ->SetZoomLevel(4.0);
   LoadHTML(
       "<object id='plugin' data='http://otherorigin.com/fake.swf' "
       "    type='application/x-ppapi-tests' width='400' height='200'>"
       "</object>");
   VerifyPluginIsThrottled(GetActiveWebContents(), "plugin");
 }