[exp] ash: Ash in Mus.

ash/host/ash_window_tree_host.cc

Index: ash/host/ash_window_tree_host.cc
diff --git a/ash/host/ash_window_tree_host.cc b/ash/host/ash_window_tree_host.cc
index 6f18204aa2f9b854c31bdacb658cbd1dee4e1d74..1cb761ff40c48eeaee45aa2c2921cada547a9b8d 100644
--- a/ash/host/ash_window_tree_host.cc
+++ b/ash/host/ash_window_tree_host.cc
@@ -4,13 +4,31 @@
 
 #include "ash/host/ash_window_tree_host.h"
 
+#include "ash/host/ash_window_tree_host_init_params.h"
+#include "ash/host/ash_window_tree_host_unified.h"
 #include "ui/aura/client/screen_position_client.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/events/event.h"
 #include "ui/gfx/geometry/rect.h"
 
+#if defined(USE_OZONE)
+#include "ash/host/ash_window_tree_host_ozone.h"
+#elif defined(USE_X11)
+#include "ash/host/ash_window_tree_host_x11.h"
+#elif defined(OS_WIN)
+#include "ash/host/ash_window_tree_host_win.h"
+#else
+#error Unsupported platform.
+#endif
+
 namespace ash {
 
+namespace {
+
+AshWindowTreeHost::Factory g_factory;
+
+}  // namespace
+
 AshWindowTreeHost::AshWindowTreeHost() : input_method_handler_(nullptr) {
 }
 
@@ -39,4 +57,26 @@ void AshWindowTreeHost::TranslateLocatedEvent(ui::LocatedEvent* event) {
   }
 }
 
+// static
+AshWindowTreeHost* AshWindowTreeHost::Create(
+    const AshWindowTreeHostInitParams& init_params) {
+  if (!g_factory.is_null())
+    return g_factory.Run(init_params);
+  if (init_params.offscreen)
+    return new AshWindowTreeHostUnified(init_params.initial_bounds);
+#if defined(USE_OZONE)
+  return new AshWindowTreeHostOzone(init_params.initial_bounds);
+#elif defined(USE_X11)
+  return new AshWindowTreeHostX11(init_params.initial_bounds);
+#elif defined(OS_WIN)
+  return new AshWindowTreeHostWin(init_params.initial_bounds);
+#endif
+  NOTREACHED();
+  return nullptr;
+}
+
+void AshWindowTreeHost::SetFactory(const Factory& factory) {
+  g_factory = factory;
+}
+
 }  // namespace ash