Add a way to fetch window frame metrics from NativeShellWindow

chrome/browser/ui/extensions/shell_window.cc

Index: chrome/browser/ui/extensions/shell_window.cc
diff --git a/chrome/browser/ui/extensions/shell_window.cc b/chrome/browser/ui/extensions/shell_window.cc
index 46e709f5dbe6304691a37f31920e8cd4107b8eba..7b675c92a48ba86349c40f57c5ca67a2e3718ad3 100644
--- a/chrome/browser/ui/extensions/shell_window.cc
+++ b/chrome/browser/ui/extensions/shell_window.cc
@@ -289,10 +289,14 @@ void ShellWindow::OnNativeClose() {
   delete this;
 }
 
-BaseWindow* ShellWindow::GetBaseWindow() {
+NativeShellWindow* ShellWindow::GetBaseWindow() {
   return native_window_.get();
 }
 
+gfx::NativeWindow ShellWindow::GetNativeWindow() {
+  return GetBaseWindow()->GetNativeWindow();
+}
+
 string16 ShellWindow::GetTitle() const {
   // WebContents::GetTitle() will return the page's URL if there's no <title>
   // specified. However, we'd prefer to show the name of the extension in that