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

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index daf80cbdeceb6015c871c26b37ddaedf1161827e..8e20a5bf364775df59ba3093eb0a47ac202bec53 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -2270,6 +2270,12 @@ bool RenderWidgetHostViewAura::LockMouse() {
   mouse_locked_ = true;
 #if !defined(OS_WIN)
   window_->SetCapture();
+#else
+  if (gfx::Screen::GetScreenFor(window_) ==
+      gfx::Screen::GetNativeScreen()) {
+    RECT window_rect = window_->GetBoundsInScreen().ToRECT();
+    ::ClipCursor(&window_rect);
+  }
 #endif
   aura::client::CursorClient* cursor_client =
       aura::client::GetCursorClient(root_window);
@@ -2283,8 +2289,6 @@ bool RenderWidgetHostViewAura::LockMouse() {
     window_->MoveCursorTo(gfx::Rect(window_->bounds().size()).CenterPoint());
   }
   tooltip_disabler_.reset(new aura::client::ScopedTooltipDisabler(root_window));
-
-  root_window->GetHost()->ConfineCursorToRootWindow();

[oshima, 2014/03/26 00:56:03]

This was added in https://codereview.chromium.org/49383004
but this makes sense only on Windows. This is no-op and not necessary on
linux_aura and is actually wrong on cros.

[Ben Goodger (Google), 2014/03/26 05:11:08]

Maybe peel this out as a separate CL?

   return true;
 }
 
@@ -2299,6 +2303,8 @@ void RenderWidgetHostViewAura::UnlockMouse() {
 
 #if !defined(OS_WIN)
   window_->ReleaseCapture();
+#else
+  ::ClipCursor(NULL);
 #endif
   window_->MoveCursorTo(unlocked_mouse_position_);
   aura::client::CursorClient* cursor_client =
@@ -2309,7 +2315,6 @@ void RenderWidgetHostViewAura::UnlockMouse() {
   }
 
   host_->LostMouseLock();
-  root_window->GetHost()->UnConfineCursor();
 }
 
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