IME for Mus: Make InputMethodMus use the IME Mojo API.

services/ui/public/interfaces/ime.mojom

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module ui.mojom;
 
 import "ui/events/mojo/event.mojom";
 import "ui/gfx/geometry/mojo/geometry.mojom";
 
 struct CompositionEvent {
@@ skipping 75 matching lines @@
 // This interface is provided by IME drivers, and also by Mus as a lightweight
 // proxy between IME drivers and clients.
 interface InputMethod {
   OnTextInputModeChanged(TextInputMode text_input_mode);
   OnTextInputTypeChanged(TextInputType text_input_type);
 
   // Client sends |caret_bounds| in focused window coordinates,
   // Mus translates it to global coordinates and sends it to IME app.
   OnCaretBoundsChanged(gfx.mojom.Rect caret_bounds);
 
+  // Called to process a key event. If InputMethod handles the event, it will
+  // notify the client of the resulting composition events (there might be none)
+  // by calling TextInputClient::OnCompositionEvent(). If the event is not
+  // handled by InputMethod, TextInputClient::OnUnhandledEvent() is called.
   ProcessKeyEvent(ui.mojom.Event key_event);
+
   CancelComposition();
 };
 
 // IME drivers send updates to clients using the TextInputClient interface.
 interface TextInputClient {
   // Corresponds to "input method result" functions of ui::TextInputClient.
+  // See comments for InputMethod::ProcessKeyEvent() for when this is called.
   OnCompositionEvent(CompositionEvent event);
 
+  // See comments for InputMethod::ProcessKeyEvent() for when this is called.
+  OnUnhandledEvent(ui.mojom.Event key_event);
+
   // TODO(moshayedi): Add functions corresponding to ui::TextInputClient for:
   // - Input text confirmation
   // - Document content operations
   // - Miscellaneous functions
   // crbug.com/631527.
 };