views/mus: WindowTreeHostMus doesn't need to know about SurfaceType.

NativeWidgetMus sets up the context-factory for the WindowTreeHostMus,
and so WindowTreeHostMus doesn't need to know about the surface-type.

BUG=none

Review URL: https://codereview.chromium.org/1647483002

Cr-Commit-Position: refs/heads/master@{#371873}

ui/views/mus/native_widget_mus.cc

@@ -307,8 +307,7 @@ void NativeWidgetMus::InitNativeWidget(const Widget::InitParams& params) {
     }
     aura::Env::GetInstance()->set_context_factory(context_factory_.get());
   }
-  window_tree_host_.reset(
-      new WindowTreeHostMus(shell_, this, window_, surface_type_));
+  window_tree_host_.reset(new WindowTreeHostMus(shell_, this, window_));
   window_tree_host_->AddObserver(this);
   window_tree_host_->InitHost();
   aura::Env::GetInstance()->set_context_factory(default_context_factory);

ui/views/mus/window_tree_host_mus.cc

@@ -18,8 +18,7 @@ namespace views {
 
 WindowTreeHostMus::WindowTreeHostMus(mojo::Shell* shell,
                                      NativeWidgetMus* native_widget,
-                                     mus::Window* window,
-                                     mus::mojom::SurfaceType surface_type)
+                                     mus::Window* window)
     : native_widget_(native_widget),
       show_state_(ui::PLATFORM_WINDOW_STATE_UNKNOWN) {
   SetPlatformWindow(

ui/views/mus/window_tree_host_mus.h

@@ -6,7 +6,6 @@
 #define UI_VIEWS_MUS_WINDOW_TREE_HOST_MUS_H_
 
 #include "base/macros.h"
-#include "components/mus/public/interfaces/window_tree.mojom.h"
 #include "ui/aura/window_tree_host_platform.h"
 #include "ui/views/mus/mus_export.h"
 
@@ -30,8 +29,7 @@ class VIEWS_MUS_EXPORT WindowTreeHostMus : public aura::WindowTreeHostPlatform {
  public:
   WindowTreeHostMus(mojo::Shell* shell,
                     NativeWidgetMus* native_widget_,
-                    mus::Window* window,
-                    mus::mojom::SurfaceType surface_type);
+                    mus::Window* window);
   ~WindowTreeHostMus() override;
 
   PlatformWindowMus* platform_window();