Remove PRODUCT_STRING_PATH from chrome_constants.h on Windows.

chrome/chrome_watcher/chrome_watcher_main_api.h

 // Copyright 2015 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_CHROME_WATCHER_CHROME_WATCHER_MAIN_API_H_
 #define CHROME_CHROME_WATCHER_CHROME_WATCHER_MAIN_API_H_
 
 #include <Windows.h>
 #include "base/files/file_path.h"
 #include "base/process/process_handle.h"
@@ skipping 11 matching lines @@
 // Watches |parent_process|, whose main thread ID is |main_thread_id|, and
 // records its exit code under |registry_path| in HKCU. A window named
 // |message_window_name|, owned by |parent_process|, will be monitored for
 // responsiveness. If SyzyASAN is enabled, a Kasko reporter process is also
 // instantiated, using |browser_data_directory| to store crash reports.
 // |on_initialized_event| will be signaled once the watcher process is fully
 // initialized. Takes ownership of |parent_process| and |on_initialized_event|.
 // |channel_name| is the current Chrome distribution channel (one of
 // installer::kChromeChannelXXX).
 typedef int (*ChromeWatcherMainFunction)(
-    const base::char16* registry_path,
+    const base::string16& registry_path,
     HANDLE parent_process,
     DWORD main_thread_id,
     HANDLE on_initialized_event,
     const base::char16* browser_data_directory,
     const base::char16* message_window_name,
     const base::char16* channel_name);
 
 // Returns an RPC endpoint name for the identified client process. This method
 // may be invoked in both the client and the watcher process with the PID of the
 // client process to establish communication between the two using a common
 // endpoint name.
 base::string16 GetKaskoEndpoint(base::ProcessId client_process_id);
 
 #endif  // CHROME_CHROME_WATCHER_CHROME_WATCHER_MAIN_API_H_