Correct ENABLE_MEDIA_ROUTER defines to fix compilation without it.

chrome/browser/extensions/component_extensions_whitelist/whitelist.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 "chrome/browser/extensions/component_extensions_whitelist/whitelist.h"
 
 #include "base/logging.h"
 #include "base/macros.h"
 #include "chrome/browser/bookmarks/enhanced_bookmarks_features.h"
 #include "chrome/common/extensions/extension_constants.h"
@@ skipping 10 matching lines @@
 #include "grit/keyboard_resources.h"
 #include "ui/file_manager/grit/file_manager_resources.h"
 #endif
 
 namespace extensions {
 
 bool IsComponentExtensionWhitelisted(const std::string& extension_id) {
   const char* allowed[] = {
     extension_misc::kHotwordSharedModuleId,
     extension_misc::kInAppPaymentsSupportAppId,
+#if defined(ENABLE_MEDIA_ROUTER)
     extension_misc::kMediaRouterStableExtensionId,
+#endif  // defined(ENABLE_MEDIA_ROUTER)
     extension_misc::kPdfExtensionId,
 #if defined(OS_CHROMEOS)
     extension_misc::kChromeVoxExtensionId,
     extension_misc::kSpeechSynthesisExtensionId,
     extension_misc::kZIPUnpackerExtensionId,
 #endif
   };
 
   for (size_t i = 0; i < arraysize(allowed); ++i) {
     if (extension_id == allowed[i])
@@ skipping 77 matching lines @@
   }
 
   LOG(ERROR) << "Component extension with manifest resource id "
              << manifest_resource_id << " not in whitelist and is not being "
              << "loaded as a result.";
   NOTREACHED();
   return false;
 }
 
 }  // namespace extensions