Enable Config::MUS to use classic IME instead of servicified IME.

ash/display/window_tree_host_manager.cc

 // Copyright (c) 2012 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.
 
 #include "ash/display/window_tree_host_manager.h"
 
 #include <algorithm>
 #include <cmath>
 #include <map>
 #include <memory>
@@ skipping 805 matching lines @@
   params_with_bounds.offscreen =
       display.id() == display::DisplayManager::kUnifiedDisplayId;
   params_with_bounds.display_id = display.id();
   params_with_bounds.device_scale_factor = display.device_scale_factor();
   params_with_bounds.ui_scale_factor = display_info.configured_ui_scale();
   // The AshWindowTreeHost ends up owned by the RootWindowControllers created
   // by this class.
   AshWindowTreeHost* ash_host =
       AshWindowTreeHost::Create(params_with_bounds).release();
   aura::WindowTreeHost* host = ash_host->AsWindowTreeHost();
-  // TODO: Config::MUS should not install an InputMethod.
-  // http://crbug.com/706913
-  if (!host->has_input_method()) {
-    if (!input_method_) {  // Singleton input method instance for Ash.
-      input_method_ = ui::CreateInputMethod(this, host->GetAcceleratedWidget());
-      // Makes sure the input method is focused by default when created, because
-      // Ash uses singleton InputMethod and it won't call OnFocus/OnBlur when
-      // the active window changed.
-      input_method_->OnFocus();
-      input_method_event_handler_.reset(
-          new InputMethodEventHandler(input_method_.get()));
-    }
-    host->SetSharedInputMethod(input_method_.get());
-    ash_host->set_input_method_handler(input_method_event_handler_.get());
+  DCHECK(!host->has_input_method());

[sky, 2017/05/03 15:25:27]

The plan is to use this code for both mash and mus. For the mash case IME will
be hosted by chrome, for the mus case we want what you have here. So, doesn't
this code need to know the ash::Config so that it conditionally set the
InputMethod?

[Hadi, 2017/05/03 19:35:42]

Done.

+  if (!input_method_) {  // Singleton input method instance for Ash.
+    input_method_ = ui::CreateInputMethod(this, host->GetAcceleratedWidget());
+    // Makes sure the input method is focused by default when created, because
+    // Ash uses singleton InputMethod and it won't call OnFocus/OnBlur when
+    // the active window changed.
+    input_method_->OnFocus();
+    input_method_event_handler_.reset(
+        new InputMethodEventHandler(input_method_.get()));
   }
+  host->SetSharedInputMethod(input_method_.get());
+  ash_host->set_input_method_handler(input_method_event_handler_.get());
 
   host->window()->SetName(base::StringPrintf(
       "%sRootWindow-%d", params_with_bounds.offscreen ? "Offscreen" : "",
       host_count++));
   host->window()->SetTitle(base::UTF8ToUTF16(display_info.name()));
   host->compositor()->SetBackgroundColor(SK_ColorBLACK);
   // No need to remove our observer observer because the WindowTreeHostManager
   // outlives the host.
   host->AddObserver(this);
   InitRootWindowSettings(host->window())->display_id = display.id();
   host->InitHost();
   host->window()->Show();
 
   window_tree_hosts_[display.id()] = ash_host;
   SetDisplayPropertiesOnHost(ash_host, display);
 
   if (switches::ConstrainPointerToRoot())
     ash_host->ConfineCursorToRootWindow();
   return ash_host;
 }
 
 }  // namespace ash