Introdcue AshWindowTreeHost and move ash/chrome specific code in WTH to ash.

ui/aura/remote_window_tree_host_win.cc

Index: ui/aura/remote_window_tree_host_win.cc
diff --git a/ui/aura/remote_window_tree_host_win.cc b/ui/aura/remote_window_tree_host_win.cc
index 19715ba4f3ff8e9aab10a125270a42b7a9d1405d..92e217c6aa89cac652d6060222463a5b70b1c331 100644
--- a/ui/aura/remote_window_tree_host_win.cc
+++ b/ui/aura/remote_window_tree_host_win.cc
@@ -390,9 +390,6 @@ void RemoteWindowTreeHostWin::Hide() {
   NOTIMPLEMENTED();
 }
 
-void RemoteWindowTreeHostWin::ToggleFullScreen() {
-}
-
 gfx::Rect RemoteWindowTreeHostWin::GetBounds() const {
   return gfx::Rect(window_size_);
 }
@@ -402,13 +399,6 @@ void RemoteWindowTreeHostWin::SetBounds(const gfx::Rect& bounds) {
   OnHostResized(bounds.size());
 }
 
-gfx::Insets RemoteWindowTreeHostWin::GetInsets() const {
-  return gfx::Insets();
-}
-
-void RemoteWindowTreeHostWin::SetInsets(const gfx::Insets& insets) {
-}
-
 gfx::Point RemoteWindowTreeHostWin::GetLocationOnNativeScreen() const {
   return gfx::Point(0, 0);
 }
@@ -433,13 +423,6 @@ bool RemoteWindowTreeHostWin::QueryMouseLocation(gfx::Point* location_return) {
   return true;
 }
 
-bool RemoteWindowTreeHostWin::ConfineCursorToRootWindow() {
-  return true;
-}
-
-void RemoteWindowTreeHostWin::UnConfineCursor() {
-}
-
 void RemoteWindowTreeHostWin::SetCursorNative(gfx::NativeCursor native_cursor) {
   if (!host_)
     return;