PNaCl on-demand installs: Make a separate async IPC to check if PNaCl is installed

chrome/browser/nacl_host/nacl_file_host.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_NACL_HOST_NACL_FILE_HOST_H_
 #define CHROME_BROWSER_NACL_HOST_NACL_FILE_HOST_H_
 
 #include <string>
 
 #include "base/callback_forward.h"
 #include "base/memory/ref_counted.h"
 
 class ExtensionInfoMap;
 class GURL;
 class NaClHostMessageFilter;
 
 namespace base {
 class FilePath;
 }
 
 namespace IPC {
 class Message;
 }
 
 // Opens NaCl Files in the Browser process, on behalf of the NaCl plugin.
 
 namespace nacl_file_host {
+typedef base::Callback<void(bool)> InstallCallback;
+typedef base::Callback<void(int64_t, int64_t)> InstallProgressCallback;
 
-// Open a Pnacl file (readonly) on behalf of the NaCl plugin.
+// Ensure that PNaCl is installed.  Calls |done_callback| if PNaCl is already
+// installed.  Otherwise, issues a request to install and calls |done_callback|
+// after that request completes w/ success or failure.
+// If an request to install is issued, then |progress_callback| is called
+// with progress updates.
+void EnsurePnaclInstalled(
+    const InstallCallback& done_callback,
+    const InstallProgressCallback& progress_callback);
+
+// Open a PNaCl file (readonly) on behalf of the NaCl plugin.
 void GetReadonlyPnaclFd(
     scoped_refptr<NaClHostMessageFilter> nacl_host_message_filter,
     const std::string& filename,
     IPC::Message* reply_msg);
 
 // Return true if the filename requested is valid for opening.
 // Sets file_to_open to the base::FilePath which we will attempt to open.
 bool PnaclCanOpenFile(const std::string& filename,
                       base::FilePath* file_to_open);
 
 // Opens a NaCl executable file for reading and executing.
 void OpenNaClExecutable(
     scoped_refptr<NaClHostMessageFilter> nacl_host_message_filter,
     scoped_refptr<ExtensionInfoMap> extension_info_map,
     int render_view_id,
     const GURL& file_url,
     IPC::Message* reply_msg);
 
 }  // namespace nacl_file_host
 
 #endif  // CHROME_BROWSER_NACL_HOST_NACL_FILE_HOST_H_