Implement Linux IME support

services/native_viewport/native_viewport_impl.h

Index: services/native_viewport/native_viewport_impl.h
diff --git a/services/native_viewport/native_viewport_impl.h b/services/native_viewport/native_viewport_impl.h
index 3391e8830d0f97dec9a3a09c564bca0c50eac05e..0c8bfca2fd64397f4d6b5060cf50561bded290f8 100644
--- a/services/native_viewport/native_viewport_impl.h
+++ b/services/native_viewport/native_viewport_impl.h
@@ -56,6 +56,8 @@ class NativeViewportImpl : public mojo::NativeViewport,
       mojo::InterfaceRequest<mojo::ContextProvider> request) override;
   void SetEventDispatcher(
       mojo::NativeViewportEventDispatcherPtr dispatcher) override;
+  void SetKeyEventDispatcher(
+      mojo::NativeViewportEventDispatcherPtr dispatcher) override;
 
   // PlatformViewport::Delegate implementation.
   void OnMetricsChanged(mojo::ViewportMetricsPtr metrics) override;
@@ -79,6 +81,7 @@ class NativeViewportImpl : public mojo::NativeViewport,
   CreateCallback create_callback_;
   RequestMetricsCallback metrics_callback_;
   mojo::NativeViewportEventDispatcherPtr event_dispatcher_;
+  mojo::NativeViewportEventDispatcherPtr key_event_dispatcher_;
   mojo::StrongBinding<mojo::NativeViewport> binding_;
 
   // Set of pointer_ids we've sent a move to and are waiting on an ack.