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      1 // Copyright (c) 2010 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 CHROME_BROWSER_ABOUT_FLAGS_H_
      6 #define CHROME_BROWSER_ABOUT_FLAGS_H_
      7 #pragma once
      8 
      9 #include <map>
     10 #include <string>
     11 
     12 #include "base/command_line.h"
     13 
     14 class ListValue;
     15 class PrefService;
     16 
     17 namespace about_flags {
     18 
     19 // Enumeration of OSs.
     20 // This is exposed only for testing.
     21 enum { kOsMac = 1 << 0, kOsWin = 1 << 1, kOsLinux = 1 << 2 , kOsCrOS = 1 << 3 };
     22 
     23 // Experiment is used internally by about_flags to describe an experiment (and
     24 // for testing).
     25 // This is exposed only for testing.
     26 struct Experiment {
     27   enum Type {
     28     // An experiment with a single value. This is typically what you want.
     29     SINGLE_VALUE,
     30 
     31     // The experiment has multiple values only one of which is ever enabled.
     32     // The first of the values should correspond to a deactivated state for this
     33     // lab (i.e. no command line option). For MULTI_VALUE experiments the
     34     // command_line of the Experiment is not used. If the experiment is enabled
     35     // the command line of the selected Choice is enabled.
     36     MULTI_VALUE,
     37   };
     38 
     39   // Used for MULTI_VALUE types to describe one of the possible values the user
     40   // can select.
     41   struct Choice {
     42     // ID of the message containing the choice name.
     43     int description_id;
     44 
     45     // Command line switch and value to enabled for this choice.
     46     const char* command_line_switch;
     47     // Simple switches that have no value should use "" for command_line_value.
     48     const char* command_line_value;
     49   };
     50 
     51   // The internal name of the experiment. This is never shown to the user.
     52   // It _is_ however stored in the prefs file, so you shouldn't change the
     53   // name of existing flags.
     54   const char* internal_name;
     55 
     56   // String id of the message containing the experiment's name.
     57   int visible_name_id;
     58 
     59   // String id of the message containing the experiment's description.
     60   int visible_description_id;
     61 
     62   // The platforms the experiment is available on
     63   // Needs to be more than a compile-time #ifdef because of profile sync.
     64   unsigned supported_platforms;  // bitmask
     65 
     66   // Type of experiment.
     67   Type type;
     68 
     69   // The commandline switch and value that are added when this lab is active.
     70   // This is different from |internal_name| so that the commandline flag can be
     71   // renamed without breaking the prefs file.
     72   // This is used if type is SINGLE_VALUE.
     73   const char* command_line_switch;
     74   // Simple switches that have no value should use "" for command_line_value.
     75   const char* command_line_value;
     76 
     77   // This is used if type is MULTI_VALUE.
     78   const Choice* choices;
     79 
     80   // Number of |choices|.
     81   // This is used if type is MULTI_VALUE.
     82   int num_choices;
     83 };
     84 
     85 // Reads the Labs |prefs| (called "Labs" for historical reasons) and adds the
     86 // commandline flags belonging to the active experiments to |command_line|.
     87 void ConvertFlagsToSwitches(PrefService* prefs, CommandLine* command_line);
     88 
     89 // Get a list of all available experiments. The caller owns the result.
     90 ListValue* GetFlagsExperimentsData(PrefService* prefs);
     91 
     92 // Returns true if one of the experiment flags has been flipped since startup.
     93 bool IsRestartNeededToCommitChanges();
     94 
     95 // Enables or disables the experiment with id |internal_name|.
     96 void SetExperimentEnabled(
     97     PrefService* prefs, const std::string& internal_name, bool enable);
     98 
     99 // Removes all switches that were added to a command line by a previous call to
    100 // |ConvertFlagsToSwitches()|.
    101 void RemoveFlagsSwitches(
    102     std::map<std::string, CommandLine::StringType>* switch_list);
    103 
    104 // Returns the value for the current platform. This is one of the values defined
    105 // by the OS enum above.
    106 // This is exposed only for testing.
    107 int GetCurrentPlatform();
    108 
    109 // Sends UMA stats about experimental flag usage. This should be called once per
    110 // startup.
    111 void RecordUMAStatistics(const PrefService* prefs);
    112 
    113 namespace testing {
    114 // Clears internal global state, for unit tests.
    115 void ClearState();
    116 
    117 // Sets the list of experiments. Pass in NULL to use the default set. This does
    118 // NOT take ownership of the supplied Experiments.
    119 void SetExperiments(const Experiment* e, size_t count);
    120 
    121 // Returns the current set of experiments.
    122 const Experiment* GetExperiments(size_t* count);
    123 
    124 // Separator used for multi values. Multi values are represented in prefs as
    125 // name-of-experiment + kMultiSeparator + selected_index.
    126 extern const char kMultiSeparator[];
    127 
    128 }  // namespace testing
    129 
    130 }  // namespace about_flags
    131 
    132 #endif  // CHROME_BROWSER_ABOUT_FLAGS_H_
    133