End gesture drag when mouse capture is lost

We grab mouse capture when either a mouse drag or a touch drag starts. Capture
loss should end the drag irrespective of which drag is in progress.

BUG=490497
TEST=ToplevelWindowEventHandlerTest.GestureDragCaptureLoss

Review URL: https://codereview.chromium.org/1156013002

Cr-Commit-Position: refs/heads/master@{#331299}

3 files changed, 44 insertions, 6 deletions

diff --git a/ash/wm/toplevel_window_event_handler.cc b/ash/wm/toplevel_window_event_handler.cc
index cc0362e..667fc52 100644
--- a/ash/wm/toplevel_window_event_handler.cc
+++ b/ash/wm/toplevel_window_event_handler.cc
@@ -190,6 +190,13 @@ void ToplevelWindowEventHandler::OnMouseEvent(
       (ui::EF_MIDDLE_MOUSE_BUTTON | ui::EF_RIGHT_MOUSE_BUTTON)) != 0)
     return;
 
+  if (event->type() == ui::ET_MOUSE_CAPTURE_CHANGED) {
+    // Capture is grabbed when both gesture and mouse drags start. Handle
+    // capture loss regardless of which type of drag is in progress.
+    HandleCaptureLost(event);
+    return;
+  }
+
   if (in_gesture_drag_)
     return;
 
@@ -201,7 +208,6 @@ void ToplevelWindowEventHandler::OnMouseEvent(
     case ui::ET_MOUSE_DRAGGED:
       HandleDrag(target, event);
       break;
-    case ui::ET_MOUSE_CAPTURE_CHANGED:
     case ui::ET_MOUSE_RELEASED:
       HandleMouseReleased(target, event);
       break;
@@ -512,11 +518,8 @@ void ToplevelWindowEventHandler::HandleMousePressed(
 void ToplevelWindowEventHandler::HandleMouseReleased(
     aura::Window* target,
     ui::MouseEvent* event) {
-  if (event->phase() != ui::EP_PRETARGET)
-    return;
-
-  CompleteDrag(event->type() == ui::ET_MOUSE_RELEASED ?
-                   DRAG_COMPLETE : DRAG_REVERT);
+  if (event->phase() == ui::EP_PRETARGET)
+    CompleteDrag(DRAG_COMPLETE);
 }
 
 void ToplevelWindowEventHandler::HandleDrag(
@@ -579,6 +582,11 @@ void ToplevelWindowEventHandler::HandleMouseExited(
     controller->HideShadow(target);
 }
 
+void ToplevelWindowEventHandler::HandleCaptureLost(ui::LocatedEvent* event) {
+  if (event->phase() == ui::EP_PRETARGET)
+    CompleteDrag(DRAG_REVERT);
+}
+
 void ToplevelWindowEventHandler::SetWindowStateTypeFromGesture(
     aura::Window* window,
     wm::WindowStateType new_state_type) {
diff --git a/ash/wm/toplevel_window_event_handler.h b/ash/wm/toplevel_window_event_handler.h
index a51eb5c..bcaaa91 100644
--- a/ash/wm/toplevel_window_event_handler.h
+++ b/ash/wm/toplevel_window_event_handler.h
@@ -89,6 +89,9 @@ class ASH_EXPORT ToplevelWindowEventHandler
   // Called for mouse exits to hide window resize shadows.
   void HandleMouseExited(aura::Window* target, ui::LocatedEvent* event);
 
+  // Called when mouse capture is lost.
+  void HandleCaptureLost(ui::LocatedEvent* event);
+
   // Sets |window|'s state type to |new_state_type|. Called after the drag has
   // been completed for fling gestures.
   void SetWindowStateTypeFromGesture(aura::Window* window,
diff --git a/ash/wm/toplevel_window_event_handler_unittest.cc b/ash/wm/toplevel_window_event_handler_unittest.cc
index 1f2acb7..bec3eae 100644
--- a/ash/wm/toplevel_window_event_handler_unittest.cc
+++ b/ash/wm/toplevel_window_event_handler_unittest.cc
@@ -16,6 +16,7 @@
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/message_loop/message_loop.h"
+#include "base/thread_task_runner_handle.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/test/aura_test_base.h"
@@ -725,6 +726,32 @@ TEST_F(ToplevelWindowEventHandlerTest, CaptureLossAfterMouseRelease) {
                 aura::client::WINDOW_MOVE_SOURCE_MOUSE));
 }
 
+namespace {
+
+// Checks that |window| has capture and releases capture.
+void CheckHasCaptureAndReleaseCapture(aura::Window* window) {
+  ASSERT_TRUE(window->HasCapture());
+  window->ReleaseCapture();
+}
+
+}  // namespace
+
+// Test that releasing capture cancels an in-progress gesture drag.
+TEST_F(ToplevelWindowEventHandlerTest, GestureDragCaptureLoss) {
+  scoped_ptr<aura::Window> window(CreateWindow(HTNOWHERE));
+  ui::test::EventGenerator generator(Shell::GetPrimaryRootWindow(),
+                                     window.get());
+
+  aura::client::WindowMoveClient* move_client =
+      aura::client::GetWindowMoveClient(window->GetRootWindow());
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::Bind(&CheckHasCaptureAndReleaseCapture,
+                            base::Unretained(window.get())));
+  EXPECT_EQ(aura::client::MOVE_CANCELED,
+            move_client->RunMoveLoop(window.get(), gfx::Vector2d(),
+                                     aura::client::WINDOW_MOVE_SOURCE_TOUCH));
+}
+
 // Showing the resize shadows when the mouse is over the window edges is tested
 // in resize_shadow_and_cursor_test.cc