Disable flaky plugin tests.

chrome/test/plugin/plugin_test.cpp

 // Copyright 2008-2009, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //    * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //    * Redistributions in binary form must reproduce the above
@@ skipping 151 matching lines @@
 
 TEST_F(PluginTest, FlashOctetStream) {
   TestPlugin(L"flash-octet-stream.html", kShortWaitTimeout, false);
 }
 
 TEST_F(PluginTest, FlashSecurity) {
   TestPlugin(L"flash.html", kShortWaitTimeout, false);
 }
 
 // http://crbug.com/16114
-TEST_F(PluginTest, FlashLayoutWhilePainting) {
+// Disabled for http://crbug.com/21538
+TEST_F(PluginTest, DISABLED_FlashLayoutWhilePainting) {
   TestPlugin(L"flash-layout-while-painting.html", kShortWaitTimeout, true);
 }
 
 // http://crbug.com/8690
 TEST_F(PluginTest, DISABLED_Java) {
   TestPlugin(L"Java.html", kShortWaitTimeout, false);
 }
 
-TEST_F(PluginTest, Silverlight) {
+// Disabled for http://crbug.com/22666
+TEST_F(PluginTest, DISABLED_Silverlight) {
   TestPlugin(L"silverlight.html", kShortWaitTimeout, false);
 }