Add CSS variables feature flag to chrome://flags.

content/public/common/content_switches.h

 // Copyright (c) 2012 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.
 
 // Defines all the "content" command-line switches.
 
 #ifndef CONTENT_PUBLIC_COMMON_CONTENT_SWITCHES_H_
 #define CONTENT_PUBLIC_COMMON_CONTENT_SWITCHES_H_
 
 #include "build/build_config.h"
@@ skipping 69 matching lines @@
 extern const char kDisableWebSecurity[];
 extern const char kDisableWebSockets[];
 extern const char kDisableXSSAuditor[];
 CONTENT_EXPORT extern const char kDomAutomationController[];
 CONTENT_EXPORT extern const char kEnableAcceleratedPainting[];
 CONTENT_EXPORT extern const char kEnableAcceleratedFilters[];
 extern const char kEnableAccessibilityLogging[];
 CONTENT_EXPORT extern const char kEnableCompositingForFixedPosition[];
 extern const char kEnableCssRegions[];
 extern const char kEnableCssShaders[];
+extern const char kEnableCssVariables[];
 CONTENT_EXPORT extern const char kEnableDeviceMotion[];
 extern const char kEnableEncryptedMedia[];
 extern const char kEnableFastback[];
 CONTENT_EXPORT extern const char kEnableFixedLayout[];
 CONTENT_EXPORT extern const char kDisableFullScreen[];
 extern const char kEnablePointerLock[];
 extern const char kEnableGpuBenchmarking[];
 CONTENT_EXPORT extern const char kEnableLogging[];
 extern const char kEnableMediaSource[];
 extern const char kEnablePeerConnection[];
@@ skipping 110 matching lines @@
 
 #if defined(USE_AURA)
 CONTENT_EXPORT extern const char kFlingTapSuppressMaxDown[];
 CONTENT_EXPORT extern const char kFlingTapSuppressMaxGap[];
 CONTENT_EXPORT extern const char kTestCompositor[];
 #endif
 
 }  // namespace switches
 
 #endif  // CONTENT_PUBLIC_COMMON_CONTENT_SWITCHES_H_