Split the field trial setup code into desktop and mobile files.

chrome/browser/chrome_browser_field_trials_mobile.h

Index: chrome/browser/chrome_browser_field_trials_mobile.h
diff --git a/chrome/browser/chrome_browser_field_trials_mobile.h b/chrome/browser/chrome_browser_field_trials_mobile.h
new file mode 100644
index 0000000000000000000000000000000000000000..bf7e25eca0b1bb83277673a8d9e9e9030c03c9bb
--- /dev/null
+++ b/chrome/browser/chrome_browser_field_trials_mobile.h
@@ -0,0 +1,24 @@
+// 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 CHROME_BROWSER_CHROME_BROWSER_FIELD_TRIALS_MOBILE_H_
+#define CHROME_BROWSER_CHROME_BROWSER_FIELD_TRIALS_MOBILE_H_
+
+#include "base/basictypes.h"
+#include "base/time.h"
+
+class CommandLine;
+class PrefService;
+
+namespace chrome {
+
+// Sets up mobile-only field trials.
+// Add invocation of your field trial initialization code in this method.
+void SetupMobileFieldTrials(const CommandLine& parsed_command_line,
+                            const base::Time& install_time,
+                            PrefService* local_state);
+
+}  // end namespace chrome
+
+#endif  // CHROME_BROWSER_CHROME_BROWSER_FIELD_TRIALS_MOBILE_H_