Refactoring the ownership of ui::InputMethod.

ash/host/ash_window_tree_host_unified.h

Index: ash/host/ash_window_tree_host_unified.h
diff --git a/ash/host/ash_window_tree_host_unified.h b/ash/host/ash_window_tree_host_unified.h
index aa9ab4c36b207d333848ef298faa7b7d1c081386..f3a11103d3557db7dc138d7947ef337a15d91e9e 100644
--- a/ash/host/ash_window_tree_host_unified.h
+++ b/ash/host/ash_window_tree_host_unified.h
@@ -26,8 +26,7 @@ class DisplayInfo;
 // compositor.
 class AshWindowTreeHostUnified : public AshWindowTreeHost,
                                  public aura::WindowTreeHost,
-                                 public aura::WindowObserver,
-                                 public ui::EventSource {
+                                 public aura::WindowObserver {
  public:
   explicit AshWindowTreeHostUnified(const gfx::Rect& initial_bounds);
   ~AshWindowTreeHostUnified() override;
@@ -65,9 +64,6 @@ class AshWindowTreeHostUnified : public AshWindowTreeHost,
   // aura::WindowObserver:
   void OnWindowDestroying(aura::Window* window) override;
 
-  // ui::EventSource:
-  ui::EventProcessor* GetEventProcessor() override;
-
   std::vector<AshWindowTreeHost*> mirroring_hosts_;
 
   gfx::Rect bounds_;