mus: Implement interwindow drag and drop

services/ui/ws/event_dispatcher.cc

 // Copyright 2015 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 "services/ui/ws/event_dispatcher.h"
 
 #include <algorithm>
 
 #include "base/time/time.h"
 #include "services/ui/ws/accelerator.h"
+#include "services/ui/ws/current_drag_operation.h"
+#include "services/ui/ws/current_drag_operation_delegate.h"
 #include "services/ui/ws/display.h"
 #include "services/ui/ws/event_dispatcher_delegate.h"
 #include "services/ui/ws/server_window.h"
 #include "services/ui/ws/server_window_delegate.h"
 #include "services/ui/ws/window_coordinate_conversions.h"
 #include "services/ui/ws/window_finder.h"
 #include "ui/events/event_utils.h"
 #include "ui/gfx/geometry/point.h"
 #include "ui/gfx/geometry/point_conversions.h"
 
@@ skipping 160 matching lines @@
       delegate_->SetNativeCapture(window);
   } else {
     delegate_->ReleaseNativeCapture();
     if (!mouse_button_down_)
       UpdateCursorProviderByLastKnownLocation();
   }
 
   return true;
 }
 
+void EventDispatcher::SetDragDropSourceWindow(
+    uint32_t change_id,
+    WindowTree* window_tree,
+    ServerWindow* capture_window,
+    mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data,
+    uint32_t drag_operations) {
+  current_drag_drop_operation_.reset(
+      new CurrentDragOperation(this, change_id, window_tree, capture_window,
+                               std::move(mime_data), drag_operations));
+}
+
 void EventDispatcher::AddSystemModalWindow(ServerWindow* window) {
   modal_window_controller_.AddSystemModalWindow(window);
 }
 
 void EventDispatcher::ReleaseCaptureBlockedByModalWindow(
     const ServerWindow* modal_window) {
   if (!capture_window_)
     return;
 
   if (modal_window_controller_.IsWindowBlockedBy(capture_window_,
@@ skipping 133 matching lines @@
       (!is_mouse_event || IsOnlyOneMouseButtonDown(event.flags()));
 
   // Update mouse down state upon events which change it.
   if (is_mouse_event) {
     if (event.type() == ui::ET_POINTER_DOWN)
       mouse_button_down_ = true;
     else if (is_pointer_going_up)
       mouse_button_down_ = false;
   }
 
+  if (current_drag_drop_operation_) {
+    const PointerTarget target = PointerTargetForEvent(event);
+    const ClientSpecificId client_id = delegate_->GetEventTargetClientId(
+        target.window, target.in_nonclient_area);
+    current_drag_drop_operation_->DispatchLocatedEvent(event, target.window,
+                                                       client_id);
+    return;
+  }
+
   if (capture_window_) {
     mouse_cursor_source_window_ = capture_window_;
     DispatchToClient(capture_window_, capture_window_client_id_, event);
     return;
   }
 
   const int32_t pointer_id = PointerId(event);
   if (!IsTrackingPointer(pointer_id) ||
       !pointer_targets_[pointer_id].is_pointer_down) {
     const bool any_pointers_down = AreAnyPointersDown();
@@ skipping 214 matching lines @@
   CancelPointerEventsToTarget(window);
 }
 
 void EventDispatcher::OnWindowDestroyed(ServerWindow* window) {
   CancelPointerEventsToTarget(window);
 
   if (mouse_cursor_source_window_ == window)
     mouse_cursor_source_window_ = nullptr;
 }
 
+void EventDispatcher::OnDragOver(bool success) {
+  current_drag_drop_operation_.reset();
+}
+
 }  // namespace ws
 }  // namespace ui