Extract a base class from CommandLinePrefStore

components/prefs/command_line_pref_store.h

+// Copyright (c) 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.
+
+#ifndef COMPONENTS_PREFS_COMMAND_LINE_PREF_STORE_H_
+#define COMPONENTS_PREFS_COMMAND_LINE_PREF_STORE_H_
+
+#include "base/command_line.h"
+#include "base/macros.h"
+#include "base/values.h"
+#include "components/prefs/value_map_pref_store.h"
+
+// Given {command-line, preferences}, this PrefStore apply the command-line
+// switches to their corresponding preferences.

[Bernhard Bauer, 2016/10/14 10:06:31]

Nit: Maybe something like, "Base class for a PrefStore that maps command line
switches to preferences. Subclasses should call the Apply...Switches() methods
with their own maps."?

[Menglin, 2016/10/14 17:12:04]

Done.

+class COMPONENTS_PREFS_EXPORT CommandLinePrefStore : public ValueMapPrefStore {
+ public:
+  struct SwitchToPreferenceMapEntry {

[Bernhard Bauer, 2016/10/14 10:06:31]

Can these become protected as well? 

[Menglin, 2016/10/14 17:12:04]

hmm I think if in blimp, we have 
static
BlimpClientContext::RegisterCommandLinePrefOverrides(CommandLinePrefStore*
store) {
  store->Apply*Switches(blimp_switch_map_);
}
we need to make both the struct and the methods public in order to make that
call ? wdyt?

+    const char* switch_name;
+    const char* preference_path;
+  };
+
+  // |set_value| indicates what the preference should be set to if the switch
+  // is present.
+  struct BooleanSwitchToPreferenceMapEntry {
+    const char* switch_name;
+    const char* preference_path;
+    bool set_value;
+  };
+
+  // Apply command-line switches to the corresponding preferences of the switch
+  // map, where the value associated with the switch is a string.
+  void ApplyStringSwitches(
+      const SwitchToPreferenceMapEntry string_switch_map[], size_t size);
+
+  // Apply command-line switches to the corresponding preferences of the switch
+  // map, where the value associated with the switch is a path.
+  void ApplyPathSwitches(const SwitchToPreferenceMapEntry path_switch_map[],
+                         size_t size);
+
+  // Apply command-line switches to the corresponding preferences of the switch
+  // map, where the value associated with the switch is an integer.
+  void ApplyIntegerSwitches(
+      const SwitchToPreferenceMapEntry integer_switch_map[], size_t size);
+
+  // Apply command-line switches to the corresponding preferences of the
+  // boolean switch map.
+  void ApplyBooleanSwitches(
+      const BooleanSwitchToPreferenceMapEntry boolean_switch_map[],
+      size_t size);
+
+
+ protected:
+  explicit CommandLinePrefStore(const base::CommandLine* command_line);
+  ~CommandLinePrefStore() override;
+
+  const base::CommandLine* command_line() { return command_line_; }
+
+ private:
+  // Weak reference.
+  const base::CommandLine* command_line_;
+
+  DISALLOW_COPY_AND_ASSIGN(CommandLinePrefStore);
+};
+
+#endif  // COMPONENTS_PREFS_COMMAND_LINE_PREF_STORE_H_