Change ordering of Shell event handlers:

ash/shell.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/shell.h"
 
 #include <algorithm>
 #include <string>
 
 #include "ash/accelerators/focus_manager_factory.h"
@@ skipping 519 matching lines @@
       delegate_->IsFirstRunAfterBoot());
 
   if (command_line->HasSwitch(ash::switches::kAshDisableNewLockAnimations))
     lock_state_controller_.reset(new SessionStateControllerImpl);
   else
     lock_state_controller_.reset(new LockStateControllerImpl2);
   power_button_controller_.reset(new PowerButtonController(
       lock_state_controller_.get()));
   AddShellObserver(lock_state_controller_.get());
 
+  drag_drop_controller_.reset(new internal::DragDropController);
   mouse_cursor_filter_.reset(new internal::MouseCursorEventFilter());
-  AddPreTargetHandler(mouse_cursor_filter_.get());
+  PrependPreTargetHandler(mouse_cursor_filter_.get());
 
   // Create Controllers that may need root window.
   // TODO(oshima): Move as many controllers before creating
   // RootWindowController as possible.
   visibility_controller_.reset(new AshVisibilityController);
-  drag_drop_controller_.reset(new internal::DragDropController);
   user_action_client_.reset(delegate_->CreateUserActionClient());
   window_modality_controller_.reset(
       new views::corewm::WindowModalityController);
   AddPreTargetHandler(window_modality_controller_.get());
 
   magnification_controller_.reset(
       MagnificationController::CreateInstance());
 
   partial_magnification_controller_.reset(
       new PartialMagnificationController());
@@ skipping 398 matching lines @@
 ////////////////////////////////////////////////////////////////////////////////
 // Shell, aura::client::ActivationChangeObserver implementation:
 
 void Shell::OnWindowActivated(aura::Window* gained_active,
                               aura::Window* lost_active) {
   if (gained_active)
     active_root_window_ = gained_active->GetRootWindow();
 }
 
 }  // namespace ash