app_shell: Allow window to load a normal URL

For testing purposes, allow shell.createWindow() to load a non-extension
URL.

BUG=none
TEST=none

Review URL: https://codereview.chromium.org/487533006

Cr-Commit-Position: refs/heads/master@{#291736}

extensions/shell/browser/api/shell/shell_api.cc

@@ -42,8 +42,14 @@ ExtensionFunction::ResponseAction ShellCreateWindowFunction::Run() {
   scoped_ptr<CreateWindow::Params> params(CreateWindow::Params::Create(*args_));
   EXTENSION_FUNCTION_VALIDATE(params.get());
 
-  // Convert "main.html" to "chrome-extension:/<id>/main.html".
-  GURL url = extension()->GetResourceURL(params->url);
+  GURL url(params->url);
+  if (url.GetOrigin().is_empty()) {
+    // Convert "main.html" to "chrome-extension:/<id>/main.html".
+    url = extension()->GetResourceURL(params->url);
+  } else {
+    // Load a typical "http://example.com/" URL.
+    LOG(WARNING) << "Loading non-extension URL " << url.spec();
+  }
   if (!url.is_valid())
     return RespondNow(Error(kInvalidArguments));