Makes construction of (ash)RemoteWindowTreeHostWin explicit

ash/host/ash_window_tree_host.h

Index: ash/host/ash_window_tree_host.h
diff --git a/ash/host/ash_window_tree_host.h b/ash/host/ash_window_tree_host.h
index 00626dba18435fb5a4c2249728637a229dcd24d7..1d1513bffd57260b56628509d56bc07484a32885 100644
--- a/ash/host/ash_window_tree_host.h
+++ b/ash/host/ash_window_tree_host.h
@@ -19,15 +19,17 @@ class Rect;
 }
 
 namespace ash {
+struct AshWindowTreeHostInitParams;
 class RootWindowTransformer;
 
 class ASH_EXPORT AshWindowTreeHost {
  public:
-  // Creates a new AshWindowTreeHost. The caller owns the returned value.
-  static AshWindowTreeHost* Create(const gfx::Rect& initial_bounds);
-
   virtual ~AshWindowTreeHost() {}
 
+  // Creates a new AshWindowTreeHost. The caller owns the returned value.
+  static AshWindowTreeHost* Create(
+      const AshWindowTreeHostInitParams& init_params);
+
   // Toggles the host's full screen state.
   virtual void ToggleFullScreen() = 0;