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

components/nacl/common/nacl_browser_delegate.h

 // 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_NACL_COMMON_NACL_BROWSER_DELEGATE_H_
 #define COMPONENTS_NACL_COMMON_NACL_BROWSER_DELEGATE_H_
 
 #include <string>
 
 #include "base/callback_forward.h"
@@ skipping 40 matching lines @@
   virtual bool GetUserDirectory(base::FilePath* user_dir) = 0;
   // Returns the version as a string. This string is used to invalidate
   // validator cache entries when Chromium is upgraded
   virtual std::string GetVersionString() const = 0;
   // Returns a HostFactory that hides the details of its embedder.
   virtual ppapi::host::HostFactory* CreatePpapiHostFactory(
       content::BrowserPpapiHost* ppapi_host) = 0;
   // Install PNaCl if this operation is supported. On success, the |installed|
   // callback should be called with true, and on failure (or not supported),
   // the |installed| callback should be called with false.
+  // TODO(jvoung): Add the progress callback as well.
   virtual void TryInstallPnacl(
       const base::Callback<void(bool)>& installed) = 0;
 };
 
 #endif  // COMPONENTS_NACL_COMMON_NACL_BROWSER_DELEGATE_H_