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

ash/display/root_window_transformers.cc

Index: ash/display/root_window_transformers.cc
diff --git a/ash/display/root_window_transformers.cc b/ash/display/root_window_transformers.cc
index 8774852a76c0a8911cfd4b03cd8a9edb13142249..30135ee2f4cb26a951a3a33778144873cd17efeb 100644
--- a/ash/display/root_window_transformers.cc
+++ b/ash/display/root_window_transformers.cc
@@ -10,10 +10,10 @@
 #include "ash/display/display_manager.h"
 #include "ash/magnifier/magnification_controller.h"
 #include "ash/shell.h"
+#include "ash/host/root_window_transformer.h"
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "third_party/skia/include/utils/SkMatrix44.h"
-#include "ui/aura/root_window_transformer.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/aura/window_property.h"
 #include "ui/compositor/dip_util.h"
@@ -124,7 +124,7 @@ gfx::Transform CreateInsetsAndScaleTransform(const gfx::Insets& insets,
 }
 
 // RootWindowTransformer for ash environment.
-class AshRootWindowTransformer : public aura::RootWindowTransformer {
+class AshRootWindowTransformer : public RootWindowTransformer {
  public:
   AshRootWindowTransformer(aura::Window* root,
                            const gfx::Display& display)
@@ -202,7 +202,7 @@ class AshRootWindowTransformer : public aura::RootWindowTransformer {
 // texture (bitmap) of the source display into the mirror window, so
 // the root window bounds is the same as the source display's
 // pixel size (excluding overscan insets).
-class MirrorRootWindowTransformer : public aura::RootWindowTransformer {
+class MirrorRootWindowTransformer : public RootWindowTransformer {
  public:
   MirrorRootWindowTransformer(const DisplayInfo& source_display_info,
                               const DisplayInfo& mirror_display_info) {
@@ -268,13 +268,13 @@ class MirrorRootWindowTransformer : public aura::RootWindowTransformer {
 
 }  // namespace
 
-aura::RootWindowTransformer* CreateRootWindowTransformerForDisplay(
+RootWindowTransformer* CreateRootWindowTransformerForDisplay(
     aura::Window* root,
     const gfx::Display& display) {
   return new AshRootWindowTransformer(root, display);
 }
 
-aura::RootWindowTransformer* CreateRootWindowTransformerForMirroredDisplay(
+RootWindowTransformer* CreateRootWindowTransformerForMirroredDisplay(
     const DisplayInfo& source_display_info,
     const DisplayInfo& mirror_display_info) {
   return new MirrorRootWindowTransformer(source_display_info,