Remove the 2-level input method system & InputMethodBridge.

ui/aura/window.cc

Index: ui/aura/window.cc
diff --git a/ui/aura/window.cc b/ui/aura/window.cc
index 1e293b72343b994b81641e0f7570d74d2105ce0c..4bf95d823f75bbd59696c61127df935ed63a3cd3 100644
--- a/ui/aura/window.cc
+++ b/ui/aura/window.cc
@@ -609,10 +609,6 @@ void Window::ConvertRectToTarget(const Window* source,
   rect->set_origin(origin);
 }
 
-ui::TextInputClient* Window::GetFocusedTextInputClient() {
-  return delegate_ ? delegate_->GetFocusedTextInputClient() : nullptr;
-}
-
 void Window::MoveCursorTo(const gfx::Point& point_in_window) {
   Window* root_window = GetRootWindow();
   DCHECK(root_window);