[Autofill] Add protobuf for Google Wallet risk parameters and a utility function for filling it out.

chrome/browser/autofill/risk/fingerprint.h

+// Copyright (c) 2012 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 CHROME_BROWSER_AUTOFILL_RISK_FINGERPRINT_H_
+#define CHROME_BROWSER_AUTOFILL_RISK_FINGERPRINT_H_
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+
+class PrefService;
+
+namespace gfx {
+class Rect;
+}
+
+namespace autofill {
+namespace risk {
+
+class Fingerprint;
+
+// Fills |fingerprint| with statistics that, collectively, constitute a unique
+// fingerprint for this (machine, user) pair, used for fraud prevention.

[Evan Stade, 2012/12/20 21:33:27]

This makes it sound like |fingerprint| is an out param, but outparams should not
be owned by the function. Also since it seems that ownership is transferred, I'm
confused how the caller ever gets the data back.

[Ilya Sherman, 2012/12/21 04:51:23]

Yeah, I was kind of punting on the callback issue... implemented now.

+// The |gaia_id| should be the user id for Google's authentication system.
+// The |window_bounds| should be the bounds of the containing Chrome window.
+// The |content_bounds| should be the bounds of the web contents view for the
+// page the user is interacting with.  The |prefs| should reflect the active
+// Chrome profile's user preferences.
+void GetFingerprint(int64 gaia_id,
+                    const gfx::Rect& window_rect,
+                    const gfx::Rect& content_rect,
+                    const PrefService& prefs,
+                    scoped_ptr<Fingerprint> fingerprint);
+
+}  // namespace risk
+}  // namespace autofill
+
+
+#endif  // CHROME_BROWSER_AUTOFILL_RISK_FINGERPRINT_H_