[Media Router] Add experiment control logic.

extensions/common/feature_switch.h

 // Copyright 2013 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.
 
 #ifndef EXTENSIONS_COMMON_FEATURE_SWITCH_H_
 #define EXTENSIONS_COMMON_FEATURE_SWITCH_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 21 matching lines @@
 class FeatureSwitch {
  public:
   static FeatureSwitch* easy_off_store_install();
   static FeatureSwitch* force_dev_mode_highlighting();
   static FeatureSwitch* prompt_for_external_extensions();
   static FeatureSwitch* error_console();
   static FeatureSwitch* enable_override_bookmarks_ui();
   static FeatureSwitch* extension_action_redesign();
   static FeatureSwitch* scripts_require_action();
   static FeatureSwitch* embedded_extension_options();
+#if defined(ENABLE_MEDIA_ROUTER)

[msw, 2015/10/23 20:18:43]

It's unfortunate to add so many #if define blocks; is that really good/intended?

[imcheng, 2015/10/23 21:39:27]

I agree. But it helps to minimize the unnecessary code compiled into binaries if
it is not enabled. 

+  static FeatureSwitch* media_router();

[msw, 2015/10/23 20:18:43]

nit: order after non-compile-time-switched entries (and to match .cc order)

[imcheng, 2015/10/23 21:39:27]

The formatting gets a bit tricky with it being the last field in the member
initializer list. I will reorder the definition in .cc instead?

[msw, 2015/10/23 22:30:49]

Acknowledged.

+#endif
   static FeatureSwitch* trace_app_source();
 
   enum DefaultValue {
     DEFAULT_ENABLED,
     DEFAULT_DISABLED
   };
 
   enum OverrideValue {
     OVERRIDE_NONE,
     OVERRIDE_ENABLED,
@@ skipping 41 matching lines @@
   const char* field_trial_name_;
   bool default_value_;
   OverrideValue override_value_;
 
   DISALLOW_COPY_AND_ASSIGN(FeatureSwitch);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_FEATURE_SWITCH_H_