cocoa: add experimental tabstrip keyboard focus support

chrome/common/chrome_features.cc

 // Copyright 2016 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/common/chrome_features.h"
 
 #include "extensions/features/features.h"
 #include "ppapi/features/features.h"
 
 namespace features {
@@ skipping 56 matching lines @@
 
 // Fixes for browser hang bugs are deployed in a field trial in order to measure
 // their impact. See crbug.com/478209.
 const base::Feature kBrowserHangFixesExperiment{
     "BrowserHangFixesExperiment", base::FEATURE_DISABLED_BY_DEFAULT};
 
 #if defined(OS_MACOSX)
 // Enables or disables the browser's touch bar.
 const base::Feature kBrowserTouchBar{"BrowserTouchBar",
                                      base::FEATURE_ENABLED_BY_DEFAULT};
+
+// Enables or disables keyboard focus for the tab strip.
+const base::Feature kTabStripKeyboardFocus{"TabStripKeyboardFocus",
+                                           base::FEATURE_DISABLED_BY_DEFAULT};
 #endif  // defined(OS_MACOSX)
 
 #if defined(OS_ANDROID)
 // Experiment to make Geolocation permissions in the omnibox and the default
 // search engine's search page consistent.
 const base::Feature kConsistentOmniboxGeolocation{
     "ConsistentOmniboxGeolocation", base::FEATURE_DISABLED_BY_DEFAULT};
 #endif
 
 #if defined(OS_WIN)
@@ skipping 203 matching lines @@
 // Enables or disables emoji, handwriting and voice input on opt-in IME menu.
 const base::Feature kEHVInputOnImeMenu{"EmojiHandwritingVoiceInput",
                                        base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Enables or disables flash component updates on Chrome OS.
 const base::Feature kCrosCompUpdates{"CrosCompUpdates",
                                      base::FEATURE_ENABLED_BY_DEFAULT};
 #endif  // defined(OS_CHROMEOS)
 
 }  // namespace features