Introduce //components/user_prefs, use to eliminate c/b/prefs dependency in Autofill.

components/user_prefs/user_prefs.h

Index: components/user_prefs/user_prefs.h
diff --git a/components/user_prefs/user_prefs.h b/components/user_prefs/user_prefs.h
new file mode 100644
index 0000000000000000000000000000000000000000..aaae5e951c5868eae1c0f87980da5a840c3a24de
--- /dev/null
+++ b/components/user_prefs/user_prefs.h
@@ -0,0 +1,53 @@
+// 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 COMPONENTS_USER_PREFS_USER_PREFS_H_
+#define COMPONENTS_USER_PREFS_USER_PREFS_H_
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "components/user_prefs/user_prefs_delegate.h"

[tfarina, 2013/02/27 15:17:50]

does scoped_ptr allow you to forward declare this?

+#include "components/user_prefs/user_prefs_export.h"
+
+template <typename T> struct DefaultSingletonTraits;
+class PrefService;
+
+namespace content {
+class BrowserContext;
+};

[tfarina, 2013/02/27 15:17:50]

no ; here

+
+namespace components {
+
+// Components may use preferences associated with a given user. These
+// are retrieved based on content::BrowserContext.
+//
+// This singleton is initialized by embedders, to provide other
+// components with a means of doing this lookup.
+class USER_PREFS_EXPORT UserPrefs {
+ public:
+  static UserPrefs* GetInstance();
+
+  ~UserPrefs() {}

[tfarina, 2013/02/27 15:17:50]

can you avoid inlining?

+
+  // Must be called exactly once, before any other method calls on
+  // this object. This object takes ownership of the delegate.
+  void Initialize(scoped_ptr<UserPrefsDelegate> delegate);
+
+  // Retrieves the PrefService for the user preferences tied to the
+  // given BrowserContext. Returns NULL if there is no such
+  // PrefService, or if |Initialize| has not been called.
+  PrefService* Lookup(content::BrowserContext* context);
+
+ private:
+  UserPrefs() {}

[tfarina, 2013/02/27 15:17:50]

can you avoid inlining here?

+  friend struct DefaultSingletonTraits<UserPrefs>;

[tfarina, 2013/02/27 15:17:50]

can you put this first? right after private: ?

+
+  scoped_ptr<UserPrefsDelegate> delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(UserPrefs);
+};
+
+}  // namespace components
+
+#endif  // COMPONENTS_USER_PREFS_USER_PREFS_H_