Add the partial screen magnifier to Chrome OS.

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index 2f08927ccab2034a515ff1cb8a4bf41642431dee..750ba1133b1ca882ad6041c88ee5c6afff8b2ee4 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -90,6 +90,7 @@ class MagnificationController;
 class MouseCursorEventFilter;
 class OutputConfiguratorAnimation;
 class OverlayEventFilter;
+class PartialMagnificationController;
 class ResizeShadowController;
 class RootWindowController;
 class RootWindowLayoutManager;
@@ -311,6 +312,10 @@ class ASH_EXPORT Shell : internal::SystemModalContainerEventFilterDelegate{
     return magnification_controller_.get();
   }
 
+  internal::PartialMagnificationController* partial_magnification_controller() {
+    return partial_magnification_controller_.get();
+  }
+
   // TODO(oshima): Remove methods that are moved to RootWindowController.
   Launcher* launcher();
 
@@ -451,6 +456,8 @@ class ASH_EXPORT Shell : internal::SystemModalContainerEventFilterDelegate{
   scoped_ptr<DisplayController> display_controller_;
   scoped_ptr<HighContrastController> high_contrast_controller_;
   scoped_ptr<internal::MagnificationController> magnification_controller_;
+  scoped_ptr<internal::PartialMagnificationController>

[sky, 2012/10/16 16:29:22]

Don't expose classes in the internal namespace that are used outside of ash. If
you need it outside of ash it shouldn't be in internal.

[Zachary Kuznia, 2012/11/12 08:43:46]

Done.

+      partial_magnification_controller_;
   scoped_ptr<aura::FocusManager> focus_manager_;
   scoped_ptr<aura::client::UserActionClient> user_action_client_;
   scoped_ptr<internal::MouseCursorEventFilter> mouse_cursor_filter_;