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// Copyright 2013 The Chromium Authors
// 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 <optional>
#include <string>
#include "base/memory/raw_ptr.h"
namespace base {
class CommandLine;
}
namespace extensions {
// A switch that can turn a feature on or off. Typically controlled via
// command-line switches but can be overridden, e.g., for testing.
// A note about priority:
// 1. If an override is present, the override state will be used.
// 2. If there is no switch name, the default value will be used. This is
// because certain features are specifically designed *not* to be able to
// be turned off via command-line, so we can't consult it.
// 3. If there is a switch name, and the switch is present in the command line,
// the command line value will be used.
// 4. Otherwise, the default value is used.
class FeatureSwitch {
public:
static FeatureSwitch* prompt_for_external_extensions();
static FeatureSwitch* embedded_extension_options();
static FeatureSwitch* trace_app_source();
enum DefaultValue {
DEFAULT_ENABLED,
DEFAULT_DISABLED
};
enum OverrideValue {
OVERRIDE_NONE,
OVERRIDE_ENABLED,
OVERRIDE_DISABLED
};
// A temporary override for the switch value.
class ScopedOverride {
public:
ScopedOverride(FeatureSwitch* feature, bool override_value);
ScopedOverride(const ScopedOverride&) = delete;
ScopedOverride& operator=(const ScopedOverride&) = delete;
~ScopedOverride();
private:
raw_ptr<FeatureSwitch> feature_;
FeatureSwitch::OverrideValue previous_value_;
};
// `switch_name` can be null, in which case the feature is controlled solely
// by the default and override values.
FeatureSwitch(const char* switch_name,
DefaultValue default_value);
FeatureSwitch(const base::CommandLine* command_line,
const char* switch_name,
DefaultValue default_value);
FeatureSwitch(const FeatureSwitch&) = delete;
FeatureSwitch& operator=(const FeatureSwitch&) = delete;
~FeatureSwitch();
// Consider using ScopedOverride instead.
void SetOverrideValue(OverrideValue value);
OverrideValue GetOverrideValue() const;
bool HasValue() const;
bool IsEnabled() const;
private:
std::string GetLegacyEnableFlag() const;
std::string GetLegacyDisableFlag() const;
bool ComputeValue() const;
// TODO(crbug.com/40269737): detect under BRP.
raw_ptr<const base::CommandLine, DanglingUntriaged> command_line_;
const char* switch_name_;
bool default_value_;
OverrideValue override_value_;
mutable std::optional<bool> cached_value_;
};
} // namespace extensions
#endif // EXTENSIONS_COMMON_FEATURE_SWITCH_H_
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