extensions/common/feature_switch.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef EXTENSIONS_COMMON_FEATURE_SWITCH_H_
   6 #define EXTENSIONS_COMMON_FEATURE_SWITCH_H_
   7
   8 #include <string>
   9
  10 #include "base/basictypes.h"
  11
  12 namespace base {
  13 class CommandLine;
  14 }
  15
  16 namespace extensions {
  17
  18 // A switch that can turn a feature on or off. Typically controlled via
  19 // command-line switches but can be overridden, e.g., for testing.
  20 // Can also integrate with Finch's field trials.
  21 // A note about priority:
  22 // 1. If an override is present, the override state will be used.
  23 // 2. If there is no switch name, the default value will be used. This is
  24 //    because certain features are specifically designed *not* to be able to
  25 //    be turned off via command-line, so we can't consult it (or, by extension,
  26 //    the finch config).
  27 // 3. If there is a switch name, and the switch is present in the command line,
  28 //    the command line value will be used.
  29 // 4. If there is a finch experiment associated and applicable to the machine,
  30 //    the finch value will be used.
  31 // 5. Otherwise, the default value is used.
  32 class FeatureSwitch {
  33  public:
  34   static FeatureSwitch* easy_off_store_install();
  35   static FeatureSwitch* force_dev_mode_highlighting();
  36   static FeatureSwitch* prompt_for_external_extensions();
  37   static FeatureSwitch* error_console();
  38   static FeatureSwitch* enable_override_bookmarks_ui();
  39   static FeatureSwitch* extension_action_redesign();
  40   static FeatureSwitch* scripts_require_action();
  41   static FeatureSwitch* embedded_extension_options();
  42   static FeatureSwitch* trace_app_source();
  43
  44   enum DefaultValue {
  45     DEFAULT_ENABLED,
  46     DEFAULT_DISABLED
  47   };
  48
  49   enum OverrideValue {
  50     OVERRIDE_NONE,
  51     OVERRIDE_ENABLED,
  52     OVERRIDE_DISABLED
  53   };
  54
  55   // A temporary override for the switch value.
  56   class ScopedOverride {
  57    public:
  58     ScopedOverride(FeatureSwitch* feature, bool override_value);
  59     ~ScopedOverride();
  60    private:
  61     FeatureSwitch* feature_;
  62     FeatureSwitch::OverrideValue previous_value_;
  63     DISALLOW_COPY_AND_ASSIGN(ScopedOverride);
  64   };
  65
  66   // |switch_name| can be null, in which case the feature is controlled solely
  67   // by the default and override values.
  68   FeatureSwitch(const char* switch_name,
  69                 DefaultValue default_value);
  70   FeatureSwitch(const char* switch_name,
  71                 const char* field_trial_name,
  72                 DefaultValue default_value);
  73   FeatureSwitch(const base::CommandLine* command_line,
  74                 const char* switch_name,
  75                 DefaultValue default_value);
  76   FeatureSwitch(const base::CommandLine* command_line,
  77                 const char* switch_name,
  78                 const char* field_trial_name,
  79                 DefaultValue default_value);
  80
  81   // Consider using ScopedOverride instead.
  82   void SetOverrideValue(OverrideValue value);
  83   OverrideValue GetOverrideValue() const;
  84
  85   bool IsEnabled() const;
  86
  87  private:
  88   std::string GetLegacyEnableFlag() const;
  89   std::string GetLegacyDisableFlag() const;
  90
  91   const base::CommandLine* command_line_;
  92   const char* switch_name_;
  93   const char* field_trial_name_;
  94   bool default_value_;
  95   OverrideValue override_value_;
  96
  97   DISALLOW_COPY_AND_ASSIGN(FeatureSwitch);
  98 };
  99
 100 }  // namespace extensions
 101
 102 #endif  // EXTENSIONS_COMMON_FEATURE_SWITCH_H_