mash: Use the new mus drag and drop API to get drag working in mash.

ui/views/mus/native_widget_mus.cc

Index: ui/views/mus/native_widget_mus.cc
diff --git a/ui/views/mus/native_widget_mus.cc b/ui/views/mus/native_widget_mus.cc
index 959b656065b347cef0eaa371f17eed9ab0c75cd7..35206cdcd85953b9ac48df5c217763db13035bf9 100644
--- a/ui/views/mus/native_widget_mus.cc
+++ b/ui/views/mus/native_widget_mus.cc
@@ -4,6 +4,9 @@
 
 #include "ui/views/mus/native_widget_mus.h"
 
+#include <utility>
+#include <vector>
+
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
@@ -32,10 +35,14 @@
 #include "ui/gfx/path.h"
 #include "ui/native_theme/native_theme_aura.h"
 #include "ui/platform_window/platform_window_delegate.h"
+#include "ui/views/drag_utils.h"
+#include "ui/views/mus/drag_drop_client_mus.h"
+#include "ui/views/mus/drop_target_mus.h"
 #include "ui/views/mus/window_manager_connection.h"
 #include "ui/views/mus/window_manager_constants_converters.h"
 #include "ui/views/mus/window_manager_frame_values.h"
 #include "ui/views/mus/window_tree_host_mus.h"
+#include "ui/views/widget/drop_helper.h"
 #include "ui/views/widget/native_widget_aura.h"
 #include "ui/views/widget/widget_delegate.h"
 #include "ui/views/window/custom_frame_view.h"
@@ -96,9 +103,9 @@ class FocusControllerMus : public wm::FocusController {
 
 class ContentWindowLayoutManager : public aura::LayoutManager {
  public:
-   ContentWindowLayoutManager(aura::Window* outer, aura::Window* inner)
+  ContentWindowLayoutManager(aura::Window* outer, aura::Window* inner)
       : outer_(outer), inner_(inner) {}
-   ~ContentWindowLayoutManager() override {}
+  ~ContentWindowLayoutManager() override {}
 
  private:
   // aura::LayoutManager:
@@ -523,6 +530,7 @@ NativeWidgetMus::NativeWidgetMus(internal::NativeWidgetDelegate* delegate,
       show_state_before_fullscreen_(ui::mojom::ShowState::DEFAULT),
       ownership_(Widget::InitParams::NATIVE_WIDGET_OWNS_WIDGET),
       content_(new aura::Window(this)),
+      last_drop_operation_(ui::DragDropTypes::DRAG_NONE),
       close_widget_factory_(this) {
   window_->set_input_event_handler(this);
   mus_window_observer_.reset(new MusWindowObserver(this));
@@ -704,6 +712,11 @@ void NativeWidgetMus::InitNativeWidget(const Widget::InitParams& params) {
   aura::client::SetScreenPositionClient(hosted_window,
                                         screen_position_client_.get());
 
+  drop_target_.reset(new DropTargetMus(content_));

[sky, 2016/09/23 16:14:09]

MakeUnique

[Elliot Glaysher, 2016/09/23 21:40:48]

Changed entire file to use MakeUnique.

+  window_->SetCanAcceptDrops(drop_target_.get());
+  drop_helper_.reset(new DropHelper(GetWidget()->GetRootView()));

[sky, 2016/09/23 16:14:09]

MakeUnique

+  aura::client::SetDragDropDelegate(content_, this);
+
   // TODO(erg): Remove this check when ash/mus/move_event_handler.cc's
   // direct usage of ui::Window::SetPredefinedCursor() is switched to a
   // private method on WindowManagerClient.
@@ -743,6 +756,16 @@ void NativeWidgetMus::InitNativeWidget(const Widget::InitParams& params) {
   if (!params.bounds.size().IsEmpty())
     SetBounds(params.bounds);
 
+  if (!params.parent) {

[sky, 2016/09/23 16:14:09]

I'm unclear as to why you don't create this for every NativeWidgetMus. Every
NativeWidgetMus contains a hierarchy of aura::Windows with a single root and has
a ui::Window. Don't you need to process the drag for every ui::Window?

[Elliot Glaysher, 2016/09/23 21:40:48]

I'm not sure I believe that this is true.

It appears that menus violate some of those assumptions. Without the `if
(!params.parent)' block around setting the drag drop client,MenuControllerTest.
MenuControllerReplacedDuringDrag times out. The test is set up to create
multiple NativeWidgets (a toplevel one, and one owned by MenuHost, which is a
child), and the implicit assumption made by the test is that replacing the
DragDropClient on the root window of the parent NativeWidget will change the
DragDropClient used by the child NativeWidget.

This check ensures this property. The parent NativeWidgetMus has a
DragDropClientMus, and the child NativeWidgetMus does not, and attempts to drag
something in the child NWMus bubble up to its parent.

(The test might also just be incorrect. Or NativeWidgetMus might not work
correctly with child widgets. Or something else that I'm not thinking of.)

[sky, 2016/09/26 02:12:59]

See line 541, which creates the WindowTreeHost which has an Aura::Window.
content_ is addded to it.
If you do end up sharing a DragDropClients, won't that mean the wrong ui::Window
is used as the source?

[Elliot Glaysher, 2016/09/26 20:57:29]

Disabled the test as discussed in person.

+    // On the desktop, we initialize some aura::clients on only the root
+    // window; DesktopNativeWidgetAura and NativeWidgetAura do different
+    // things. When we make a DesktopNativeWidgetMus (and that should be the
+    // root NativeWidget in programs other than the window manager), these
+    // should go there.
+    drag_drop_client_.reset(new DragDropClientMus(content_, window_));

[sky, 2016/09/23 16:14:09]

MakeUnique

+    aura::client::SetDragDropClient(hosted_window, drag_drop_client_.get());
+  }
+
   // TODO(beng): much else, see [Desktop]NativeWidgetAura.
 
   native_widget_delegate_->OnNativeWidgetCreated(false);
@@ -1150,13 +1173,13 @@ void NativeWidgetMus::FlashFrame(bool flash_frame) {
   // NOTIMPLEMENTED();
 }
 
-void NativeWidgetMus::RunShellDrag(
-    View* view,
-    const ui::OSExchangeData& data,
-    const gfx::Point& location,
-    int operation,
-    ui::DragDropTypes::DragEventSource source) {
-  // NOTIMPLEMENTED();
+void NativeWidgetMus::RunShellDrag(View* view,
+                                   const ui::OSExchangeData& data,
+                                   const gfx::Point& location,
+                                   int drag_operations,
+                                   ui::DragDropTypes::DragEventSource source) {
+  if (window_)
+    views::RunShellDrag(content_, data, location, drag_operations, source);
 }
 
 void NativeWidgetMus::SchedulePaintInRect(const gfx::Rect& rect) {
@@ -1410,6 +1433,36 @@ void NativeWidgetMus::OnHostCloseRequested(const aura::WindowTreeHost* host) {
   GetWidget()->Close();
 }
 
+////////////////////////////////////////////////////////////////////////////////
+// NativeWidgetMus, aura::WindowDragDropDelegate implementation:
+
+void NativeWidgetMus::OnDragEntered(const ui::DropTargetEvent& event) {
+  DCHECK(drop_helper_);
+  last_drop_operation_ = drop_helper_->OnDragOver(
+      event.data(), event.location(), event.source_operations());
+}
+
+int NativeWidgetMus::OnDragUpdated(const ui::DropTargetEvent& event) {
+  DCHECK(drop_helper_);
+  last_drop_operation_ = drop_helper_->OnDragOver(
+      event.data(), event.location(), event.source_operations());
+  return last_drop_operation_;
+}
+
+void NativeWidgetMus::OnDragExited() {
+  DCHECK(drop_helper_);
+  drop_helper_->OnDragExit();
+}
+
+int NativeWidgetMus::OnPerformDrop(const ui::DropTargetEvent& event) {
+  DCHECK(drop_helper_);
+  return drop_helper_->OnDrop(event.data(), event.location(),
+                              last_drop_operation_);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// NativeWidgetMus, ui::InputEventHandler implementation:
+
 void NativeWidgetMus::OnWindowInputEvent(
     ui::Window* view,
     const ui::Event& event_in,