Use ShellPtr type in ApplicationLoader instead of untyped handles

shell/android/android_handler_loader.cc

Index: shell/android/android_handler_loader.cc
diff --git a/shell/android/android_handler_loader.cc b/shell/android/android_handler_loader.cc
index a6eab42d3d99171bc9e163554e6f824f6dd95558..61b8e91cde3a90ad2fe346c5f5ae635d94b03a8f 100644
--- a/shell/android/android_handler_loader.cc
+++ b/shell/android/android_handler_loader.cc
@@ -15,11 +15,10 @@ AndroidHandlerLoader::~AndroidHandlerLoader() {
 
 void AndroidHandlerLoader::Load(ApplicationManager* manager,
                                 const GURL& url,
-                                ScopedMessagePipeHandle shell_handle,
+                                ShellPtr shell,
                                 LoadCallback callback) {
-  DCHECK(shell_handle.is_valid());
-  application_.reset(
-      new ApplicationImpl(&android_handler_, shell_handle.Pass()));
+  DCHECK(shell);
+  application_.reset(new ApplicationImpl(&android_handler_, shell.Pass()));
 }
 
 void AndroidHandlerLoader::OnApplicationError(ApplicationManager* manager,