mash: Migrate ash::DragImageView to wm common types

ash/drag_drop/drag_drop_controller.cc

Index: ash/drag_drop/drag_drop_controller.cc
diff --git a/ash/drag_drop/drag_drop_controller.cc b/ash/drag_drop/drag_drop_controller.cc
index 4ace7378a24e0e8e606f2d77116ee5b15fbdcd69..133fb35931a3477a05c965aeadfdfd5d5a24c261 100644
--- a/ash/drag_drop/drag_drop_controller.cc
+++ b/ash/drag_drop/drag_drop_controller.cc
@@ -6,8 +6,9 @@
 
 #include <utility>
 
+#include "ash/aura/wm_window_aura.h"
+#include "ash/common/drag_drop/drag_image_view.h"
 #include "ash/drag_drop/drag_drop_tracker.h"
-#include "ash/drag_drop/drag_image_view.h"
 #include "ash/shell.h"
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
@@ -134,9 +135,11 @@ DragDropController::DragDropController()
       current_drag_event_source_(ui::DragDropTypes::DRAG_EVENT_SOURCE_MOUSE),
       weak_factory_(this) {
   Shell::GetInstance()->PrependPreTargetHandler(this);
+  Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
 }
 
 DragDropController::~DragDropController() {
+  Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
   Shell::GetInstance()->RemovePreTargetHandler(this);
   Cleanup();
   if (cancel_animation_)
@@ -199,7 +202,8 @@ int DragDropController::StartDragAndDrop(
   drag_image_final_bounds_for_cancel_animation_ =
       gfx::Rect(start_location - provider->GetDragImageOffset(),
                 provider->GetDragImage().size());
-  drag_image_.reset(new DragImageView(source_window->GetRootWindow(), source));
+  drag_image_.reset(new DragImageView(
+      WmWindowAura::Get(source_window)->GetRootWindow(), source));

[msw, 2016/08/05 19:32:58]

nit: comment here on the reasoning for using WmWindow::GetRootWindow instead of
aura::Window::GetRootWindow?

[James Cook, 2016/08/05 20:10:11]

There's no good reason to change it to WmWindow::GetRootWindow, so I put it back
to aura::Window::GetRootWindow.

   drag_image_->SetImage(provider->GetDragImage());
   drag_image_offset_ = provider->GetDragImageOffset();
   gfx::Rect drag_image_bounds(start_location, drag_image_->GetPreferredSize());
@@ -537,6 +541,13 @@ void DragDropController::AnimationCanceled(const gfx::Animation* animation) {
   AnimationEnded(animation);
 }
 
+void DragDropController::OnDisplayConfigurationChanging() {
+  // Abort in-progress drags if a monitor is added or removed because the drag
+  // image widget's container may be destroyed.
+  if (IsDragDropInProgress())
+    DragCancel();
+}
+
 void DragDropController::StartCanceledAnimation(int animation_duration_ms) {
   DCHECK(drag_image_.get());
   drag_image_->SetTouchDragOperationHintOff();