mus: Implement interwindow drag and drop

services/ui/ws/drag_controller_unittest.cc

Index: services/ui/ws/drag_controller_unittest.cc
diff --git a/services/ui/ws/drag_controller_unittest.cc b/services/ui/ws/drag_controller_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..de8a5ef53ec682735bbbfec7bf20b3a2bd0d3a66
--- /dev/null
+++ b/services/ui/ws/drag_controller_unittest.cc
@@ -0,0 +1,583 @@
+// Copyright 2016 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/drag_controller.h"
+
+#include "services/ui/ws/drag_source.h"
+#include "services/ui/ws/drag_target_connection.h"
+#include "services/ui/ws/ids.h"
+#include "services/ui/ws/server_window.h"
+#include "services/ui/ws/test_server_window_delegate.h"
+#include "services/ui/ws/test_utils.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/events/base_event_utils.h"
+
+namespace ui {
+namespace ws {
+
+enum class QueuedType { NONE, ENTER, OVER, LEAVE, DROP };
+
+class DragControllerTest;
+
+// All the classes to represent a window.
+class DragTestWindow : public DragTargetConnection {
+ public:
+  struct DragEvent {
+    QueuedType type;
+    uint32_t key_state;
+    gfx::Point cursor_offset;
+    uint32_t effect_bitmask;
+    base::Callback<void(uint32_t)> callback;
+  };
+
+  DragTestWindow(DragControllerTest* parent, const WindowId& id)
+      : parent_(parent), window_delegate_(), window_(&window_delegate_, id) {
+    window_.SetCanAcceptDrops(true);
+  }
+  ~DragTestWindow() override;
+
+  TestServerWindowDelegate* delegate() { return &window_delegate_; }
+  ServerWindow* window() { return &window_; }
+
+  QueuedType queue_response_type() {
+    if (queued_callbacks_.empty())
+      return QueuedType::NONE;
+    return queued_callbacks_.front().type;
+  }
+
+  const DragEvent& queue_front() { return queued_callbacks_.front(); }
+
+  size_t queue_size() { return queued_callbacks_.size(); }
+
+  uint32_t times_received_drag_drop_start() {
+    return times_received_drag_drop_start_;
+  }
+
+  void SetParent(DragTestWindow* p) { p->window_.Add(&window_); }
+
+  void OptOutOfDrag() { window_.SetCanAcceptDrops(false); }
+
+  // Calls the callback at the front of the queue.
+  void Respond(bool respond_with_effect) {
+    if (queued_callbacks_.size()) {
+      if (!queued_callbacks_.front().callback.is_null()) {
+        queued_callbacks_.front().callback.Run(
+            respond_with_effect ? queued_callbacks_.front().effect_bitmask : 0);
+      }
+
+      queued_callbacks_.pop();
+    }
+  }
+
+  // Overridden from DragTestConnection:
+  void PerformOnDragDropStart(
+      mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data) override {
+    times_received_drag_drop_start_++;
+    mime_data_ = std::move(mime_data);
+  }
+
+  void PerformOnDragEnter(
+      const ServerWindow* window,
+      uint32_t key_state,
+      const gfx::Point& cursor_offset,
+      uint32_t effect_bitmask,
+      const base::Callback<void(uint32_t)>& callback) override {
+    DCHECK_EQ(window, &window_);
+    queued_callbacks_.push({QueuedType::ENTER, key_state, cursor_offset,
+                            effect_bitmask, callback});
+  }
+
+  void PerformOnDragOver(
+      const ServerWindow* window,
+      uint32_t key_state,
+      const gfx::Point& cursor_offset,
+      uint32_t effect_bitmask,
+      const base::Callback<void(uint32_t)>& callback) override {
+    DCHECK_EQ(window, &window_);
+    queued_callbacks_.push(
+        {QueuedType::OVER, key_state, cursor_offset, effect_bitmask, callback});
+  }
+
+  void PerformOnDragLeave(const ServerWindow* window) override {
+    DCHECK_EQ(window, &window_);
+    queued_callbacks_.push({QueuedType::LEAVE, 0, gfx::Point(), 0,
+                            base::Callback<void(uint32_t)>()});
+  }
+
+  void PerformOnCompleteDrop(
+      const ServerWindow* window,
+      uint32_t key_state,
+      const gfx::Point& cursor_offset,
+      uint32_t effect_bitmask,
+      const base::Callback<void(uint32_t)>& callback) override {
+    DCHECK_EQ(window, &window_);
+    queued_callbacks_.push(
+        {QueuedType::DROP, key_state, cursor_offset, effect_bitmask, callback});
+  }
+
+  void PerformOnDragDropDone() override { mime_data_.SetToEmpty(); }
+
+ private:
+  DragControllerTest* parent_;
+  TestServerWindowDelegate window_delegate_;
+  ServerWindow window_;
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data_;
+  uint32_t times_received_drag_drop_start_ = 0;
+
+  std::queue<DragEvent> queued_callbacks_;
+};
+
+class DragControllerTest : public testing::Test, public DragSource {
+ public:
+  std::unique_ptr<DragTestWindow> BuildWindow() {
+    WindowId id(1, ++window_id_);
+    std::unique_ptr<DragTestWindow> p =
+        base::MakeUnique<DragTestWindow>(this, id);
+    server_window_by_id_[id] = p->window();
+    connection_by_window_[p->window()] = p.get();
+    return p;
+  }
+
+  void StartDragOperation(
+      mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data,
+      DragTestWindow* window,
+      uint32_t drag_operations) {
+    window->PerformOnDragDropStart(mime_data.Clone());
+    drag_operation_.reset(new DragController(
+        this, window->window(), window, PointerEvent::kMousePointerId,
+        std::move(mime_data), drag_operations));
+  }
+
+  void DispatchDrag(DragTestWindow* window,
+                    bool mouse_released,
+                    uint32_t flags,
+                    const gfx::Point& position) {
+    ui::PointerEvent event(
+        ui::MouseEvent(mouse_released ? ET_MOUSE_RELEASED : ET_MOUSE_PRESSED,
+                       position, position, ui::EventTimeForNow(), flags, 0));
+    drag_operation_->DispatchPointerEvent(event,
+                                          window ? window->window() : nullptr);
+  }
+
+  void DispatchDragWithPointer(DragTestWindow* window,
+                               int32_t drag_pointer,
+                               bool mouse_released,
+                               uint32_t flags,
+                               const gfx::Point& position) {
+    ui::PointerEvent event(ET_POINTER_DOWN, position, position, flags,
+                           drag_pointer, 0, PointerDetails(),
+                           base::TimeTicks());
+    drag_operation_->DispatchPointerEvent(event,
+                                          window ? window->window() : nullptr);
+  }
+
+  void OnTestWindowDestroyed(DragTestWindow* test_window) {
+    drag_operation_->OnWillDestroyDragTargetConnection(test_window);
+    server_window_by_id_.erase(test_window->window()->id());
+    connection_by_window_.erase(test_window->window());
+  }
+
+  DragController* drag_operation() const { return drag_operation_.get(); }
+  const base::Optional<bool>& drag_completed_value() {
+    return drag_completed_value_;
+  }
+
+ private:
+  // Overridden from testing::Test:
+  void SetUp() override {
+    testing::Test::SetUp();
+
+    window_delegate_.reset(new TestServerWindowDelegate());
+    root_window_.reset(
+        new ServerWindow(window_delegate_.get(), WindowId(1, 2)));
+    window_delegate_->set_root_window(root_window_.get());
+    root_window_->SetVisible(true);
+  }
+
+  void TearDown() override {
+    drag_operation_.reset();
+    root_window_.reset();
+    window_delegate_.reset();
+
+    DCHECK(server_window_by_id_.empty());
+    DCHECK(connection_by_window_.empty());
+
+    testing::Test::TearDown();
+  }
+
+  // Overridden from DragControllerSource:
+  void OnDragCompleted(bool success) override {
+    drag_completed_value_ = success;
+  }
+
+  ServerWindow* GetWindowById(const WindowId& id) override {
+    auto it = server_window_by_id_.find(id);
+    if (it == server_window_by_id_.end())
+      return nullptr;
+    return it->second;
+  }
+
+  DragTargetConnection* GetDragTargetForWindow(
+      const ServerWindow* window) override {
+    auto it = connection_by_window_.find(const_cast<ServerWindow*>(window));
+    if (it == connection_by_window_.end())
+      return nullptr;
+    return it->second;
+  }
+
+  int window_id_ = 3;
+
+  std::map<WindowId, ServerWindow*> server_window_by_id_;
+  std::map<ServerWindow*, DragTargetConnection*> connection_by_window_;
+
+  std::unique_ptr<TestServerWindowDelegate> window_delegate_;
+  std::unique_ptr<ServerWindow> root_window_;
+
+  std::unique_ptr<DragController> drag_operation_;
+
+  base::Optional<bool> drag_completed_value_;
+};
+
+DragTestWindow::~DragTestWindow() {
+  parent_->OnTestWindowDestroyed(this);
+}
+
+TEST_F(DragControllerTest, SimpleDragDrop) {
+  std::unique_ptr<DragTestWindow> window = BuildWindow();
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data;
+  StartDragOperation(std::move(mime_data), window.get(),
+                     ui::mojom::kDropEffectMove);
+
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(1, 1));
+  EXPECT_EQ(QueuedType::ENTER, window->queue_response_type());
+  window->Respond(true);
+
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(2, 2));
+  EXPECT_EQ(QueuedType::OVER, window->queue_response_type());
+  window->Respond(true);
+
+  DispatchDrag(window.get(), true, 0, gfx::Point(2, 2));
+  EXPECT_EQ(QueuedType::DROP, window->queue_response_type());
+  window->Respond(true);
+
+  EXPECT_TRUE(drag_completed_value().value_or(false));
+}
+
+TEST_F(DragControllerTest, OnlyDeliverMimeDataOnce) {
+  std::unique_ptr<DragTestWindow> window1 = BuildWindow();
+  std::unique_ptr<DragTestWindow> window2 = BuildWindow();
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data;
+
+  // The client lib is responsible for sending the data to the window that's
+  // the drag source to minimize IPC.
+  EXPECT_EQ(0u, window1->times_received_drag_drop_start());
+  StartDragOperation(std::move(mime_data), window1.get(),
+                     ui::mojom::kDropEffectMove);
+  EXPECT_EQ(1u, window1->times_received_drag_drop_start());
+  DispatchDrag(window1.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(1, 1));
+  EXPECT_EQ(1u, window1->times_received_drag_drop_start());
+  window1->Respond(true);
+
+  // Window2 doesn't receive the drag data until mouse is over it.
+  EXPECT_EQ(0u, window2->times_received_drag_drop_start());
+  DispatchDrag(window2.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(2, 2));
+  EXPECT_EQ(1u, window2->times_received_drag_drop_start());
+
+  // Moving back to the source window doesn't send an additional start message.
+  DispatchDrag(window1.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(1, 1));
+  EXPECT_EQ(1u, window1->times_received_drag_drop_start());
+
+  // Moving back to window2 doesn't send an additional start message.
+  DispatchDrag(window2.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(1, 1));
+  EXPECT_EQ(1u, window2->times_received_drag_drop_start());
+}
+
+TEST_F(DragControllerTest, DeliverMessageToParent) {
+  std::unique_ptr<DragTestWindow> window1 = BuildWindow();
+  std::unique_ptr<DragTestWindow> window2 = BuildWindow();
+  std::unique_ptr<DragTestWindow> window3 = BuildWindow();
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data;
+
+  window3->SetParent(window2.get());
+  window3->OptOutOfDrag();
+
+  StartDragOperation(std::move(mime_data), window1.get(),
+                     ui::mojom::kDropEffectMove);
+
+  // Dispatching a drag to window3 (which has can accept drags off) redirects
+  // to window2, which is its parent.
+  DispatchDrag(window3.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(1, 1));
+  EXPECT_EQ(1u, window2->times_received_drag_drop_start());
+}
+
+TEST_F(DragControllerTest, FailWhenDropOverNoWindow) {
+  std::unique_ptr<DragTestWindow> window = BuildWindow();
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data;
+  StartDragOperation(std::move(mime_data), window.get(),
+                     ui::mojom::kDropEffectMove);
+
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(1, 1));
+  EXPECT_EQ(QueuedType::ENTER, window->queue_response_type());
+  window->Respond(true);
+
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(2, 2));
+  EXPECT_EQ(QueuedType::OVER, window->queue_response_type());
+  window->Respond(true);
+
+  DispatchDrag(nullptr, true, 0, gfx::Point(2, 2));
+  // Moving outside of |window| should result in |window| getting a leave.
+  EXPECT_EQ(QueuedType::LEAVE, window->queue_response_type());
+  window->Respond(true);
+
+  EXPECT_FALSE(drag_completed_value().value_or(true));
+}
+
+TEST_F(DragControllerTest, EnterLeaveWhenMovingBetweenTwoWindows) {
+  std::unique_ptr<DragTestWindow> window1 = BuildWindow();
+  std::unique_ptr<DragTestWindow> window2 = BuildWindow();
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data;
+  StartDragOperation(std::move(mime_data), window1.get(),
+                     ui::mojom::kDropEffectMove);
+
+  DispatchDrag(window1.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(1, 1));
+  EXPECT_EQ(QueuedType::ENTER, window1->queue_response_type());
+  window1->Respond(true);
+
+  DispatchDrag(window2.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(2, 2));
+  EXPECT_EQ(QueuedType::ENTER, window2->queue_response_type());
+  EXPECT_EQ(QueuedType::LEAVE, window1->queue_response_type());
+  window1->Respond(true);
+  window2->Respond(true);
+}
+
+TEST_F(DragControllerTest, DeadWindowDoesntBlock) {
+  std::unique_ptr<DragTestWindow> window1 = BuildWindow();
+  std::unique_ptr<DragTestWindow> window2 = BuildWindow();
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data;
+  StartDragOperation(std::move(mime_data), window1.get(),
+                     ui::mojom::kDropEffectMove);
+
+  test::DragControllerTestApi api(drag_operation());
+
+  // Simulate a dead window by giving it a few messages, but don't respond to
+  // them.
+  DispatchDrag(window1.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(1, 1));
+  DispatchDrag(window1.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(2, 2));
+  EXPECT_EQ(1u, window1->queue_size());
+  EXPECT_EQ(2u, api.GetSizeOfQueueForWindow(window1->window()));
+
+  // Moving to window2 should dispatch the enter event to it immediately.
+  DispatchDrag(window2.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(3, 3));
+  EXPECT_EQ(QueuedType::ENTER, window2->queue_response_type());
+  EXPECT_EQ(1u, window1->queue_size());
+}
+
+TEST_F(DragControllerTest, EnterToOverQueued) {
+  std::unique_ptr<DragTestWindow> window = BuildWindow();
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data;
+  StartDragOperation(std::move(mime_data), window.get(),
+                     ui::mojom::kDropEffectMove);
+
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(1, 1));
+  ASSERT_EQ(1u, window->queue_size());
+  EXPECT_EQ(QueuedType::ENTER, window->queue_response_type());
+  // Don't respond.
+
+  // We don't receive another message since we haven't acknowledged the first.
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(1, 2));
+  ASSERT_EQ(1u, window->queue_size());
+
+  // Responding causes us to receive our next event.
+  window->Respond(true);
+  ASSERT_EQ(1u, window->queue_size());
+  EXPECT_EQ(QueuedType::OVER, window->queue_response_type());
+}
+
+TEST_F(DragControllerTest, CoalesceMouseOverEvents) {
+  std::unique_ptr<DragTestWindow> window = BuildWindow();
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data;
+  StartDragOperation(std::move(mime_data), window.get(),
+                     ui::mojom::kDropEffectMove);
+
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(1, 1));
+  EXPECT_EQ(QueuedType::ENTER, window->queue_response_type());
+
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(1, 2));
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(2, 2));
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(2, 3));
+
+  // Responding to the first delivers us the last mouse over event's position.
+  window->Respond(true);
+  ASSERT_EQ(1u, window->queue_size());
+  EXPECT_EQ(QueuedType::OVER, window->queue_response_type());
+  EXPECT_EQ(gfx::Point(2, 3), window->queue_front().cursor_offset);
+
+  // There are no queued events because they were coalesced.
+  window->Respond(true);
+  EXPECT_EQ(0u, window->queue_size());
+}
+
+TEST_F(DragControllerTest, RemovePendingMouseOversOnLeave) {
+  std::unique_ptr<DragTestWindow> window1 = BuildWindow();
+  std::unique_ptr<DragTestWindow> window2 = BuildWindow();
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data;
+  StartDragOperation(std::move(mime_data), window1.get(),
+                     ui::mojom::kDropEffectMove);
+
+  // Enter
+  DispatchDrag(window1.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(1, 1));
+  EXPECT_EQ(QueuedType::ENTER, window1->queue_response_type());
+
+  // Over
+  DispatchDrag(window1.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(1, 1));
+
+  // Leave
+  DispatchDrag(window2.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(1, 1));
+
+  // The window finally responds to the enter message; we should not receive
+  // any over messages since we didn't respond to the enter message in time.
+  window1->Respond(true);
+  ASSERT_EQ(1u, window1->queue_size());
+  EXPECT_EQ(QueuedType::LEAVE, window1->queue_response_type());
+}
+
+TEST_F(DragControllerTest, TargetWindowClosedWhileDrag) {
+  std::unique_ptr<DragTestWindow> window1 = BuildWindow();
+  std::unique_ptr<DragTestWindow> window2 = BuildWindow();
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data;
+  StartDragOperation(std::move(mime_data), window1.get(),
+                     ui::mojom::kDropEffectMove);
+
+  test::DragControllerTestApi api(drag_operation());
+
+  // Send some events to |window|.
+  DispatchDrag(window2.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(1, 1));
+  EXPECT_EQ(QueuedType::ENTER, window2->queue_response_type());
+  DispatchDrag(window2.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(1, 1));
+
+  ServerWindow* server_window = window2->window();
+
+  // Ensure that DragController is waiting for a response from |window|.
+  EXPECT_EQ(2u, api.GetSizeOfQueueForWindow(server_window));
+  EXPECT_EQ(server_window, api.GetCurrentTarget());
+
+  // Force the destruction of |window.window|.
+  window2.reset();
+
+  // DragController doesn't know anything about the server window now.
+  EXPECT_EQ(0u, api.GetSizeOfQueueForWindow(server_window));
+  EXPECT_EQ(nullptr, api.GetCurrentTarget());
+
+  // But a target window closing out from under us doesn't fail the drag.
+  EXPECT_FALSE(drag_completed_value().has_value());
+}
+
+TEST_F(DragControllerTest, SourceWindowClosedWhileDrag) {
+  std::unique_ptr<DragTestWindow> window1 = BuildWindow();
+  std::unique_ptr<DragTestWindow> window2 = BuildWindow();
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data;
+  StartDragOperation(std::move(mime_data), window1.get(),
+                     ui::mojom::kDropEffectMove);
+
+  test::DragControllerTestApi api(drag_operation());
+
+  // Send some events to |window|.
+  DispatchDrag(window2.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(1, 1));
+  EXPECT_EQ(QueuedType::ENTER, window2->queue_response_type());
+  DispatchDrag(window2.get(), false, ui::EF_LEFT_MOUSE_BUTTON,
+               gfx::Point(1, 1));
+
+  ServerWindow* server_window = window2->window();
+
+  // Ensure that DragController is waiting for a response from |window|.
+  EXPECT_EQ(2u, api.GetSizeOfQueueForWindow(server_window));
+  EXPECT_EQ(server_window, api.GetCurrentTarget());
+
+  // Force the destruction of the source window.
+  window1.reset();
+
+  // The source window going away fails the drag.
+  EXPECT_FALSE(drag_completed_value().value_or(true));
+}
+
+TEST_F(DragControllerTest, DontQueueEventsAfterDrop) {
+  // The DragController needs to stick around to coordinate the drop, but
+  // it should ignore further mouse events during this time.
+  std::unique_ptr<DragTestWindow> window = BuildWindow();
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data;
+  StartDragOperation(std::move(mime_data), window.get(),
+                     ui::mojom::kDropEffectMove);
+
+  test::DragControllerTestApi api(drag_operation());
+
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(1, 1));
+  EXPECT_EQ(QueuedType::ENTER, window->queue_response_type());
+  window->Respond(true);
+
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(2, 2));
+  EXPECT_EQ(QueuedType::OVER, window->queue_response_type());
+  window->Respond(true);
+
+  DispatchDrag(window.get(), true, 0, gfx::Point(2, 2));
+  EXPECT_EQ(QueuedType::DROP, window->queue_response_type());
+  EXPECT_EQ(1u, api.GetSizeOfQueueForWindow(window->window()));
+
+  // Further located events don't result in additional drag messages.
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(2, 2));
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(2, 2));
+  EXPECT_EQ(1u, api.GetSizeOfQueueForWindow(window->window()));
+}
+
+TEST_F(DragControllerTest, CancelDrag) {
+  // The DragController needs to stick around to coordinate the drop, but
+  // it should ignore further mouse events during this time.
+  std::unique_ptr<DragTestWindow> window = BuildWindow();
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data;
+  StartDragOperation(std::move(mime_data), window.get(),
+                     ui::mojom::kDropEffectMove);
+
+  DispatchDrag(window.get(), false, ui::EF_LEFT_MOUSE_BUTTON, gfx::Point(1, 1));
+  EXPECT_EQ(QueuedType::ENTER, window->queue_response_type());
+  window->Respond(true);
+
+  drag_operation()->Cancel();
+
+  EXPECT_FALSE(drag_completed_value().value_or(true));
+}
+
+TEST_F(DragControllerTest, IgnoreEventsFromOtherPointers) {
+  std::unique_ptr<DragTestWindow> window = BuildWindow();
+  mojo::Map<mojo::String, mojo::Array<uint8_t>> mime_data;
+  // This starts the operation with PointerEvent::kMousePointerId.
+  StartDragOperation(std::move(mime_data), window.get(),
+                     ui::mojom::kDropEffectMove);
+
+  // Ignore events from pointer 5.
+  DispatchDragWithPointer(window.get(), 5, false, ui::EF_LEFT_MOUSE_BUTTON,
+                          gfx::Point(1, 1));
+  ASSERT_EQ(0u, window->queue_size());
+}
+
+// TODO(erg): Add a test to ensure windows that the cursor isn't over
+// responding to messages don't change the cursor when we have cursor handling
+// code.
+
+}  // namespace ws
+}  // namespace ui