mus: Use the new drag API to implement tab dragging in chrome.

ash/mus/window_manager.cc

Index: ash/mus/window_manager.cc
diff --git a/ash/mus/window_manager.cc b/ash/mus/window_manager.cc
index 87090cc9772f987dd2c3c6dfcb32f8bb6072e527..f4598bbf4f4948a3e74a2d662dc9cc8474c83df6 100644
--- a/ash/mus/window_manager.cc
+++ b/ash/mus/window_manager.cc
@@ -12,6 +12,7 @@
 #include "ash/mus/bridge/wm_lookup_mus.h"
 #include "ash/mus/bridge/wm_shell_mus.h"
 #include "ash/mus/bridge/wm_window_mus.h"
+#include "ash/mus/frame/move_event_handler.h"
 #include "ash/mus/non_client_frame_controller.h"
 #include "ash/mus/property_util.h"
 #include "ash/mus/root_window_controller.h"
@@ -26,6 +27,7 @@
 #include "components/mus/public/cpp/window_tree_client.h"
 #include "components/mus/public/interfaces/mus_constants.mojom.h"
 #include "components/mus/public/interfaces/window_manager.mojom.h"
+#include "ui/base/hit_test.h"
 #include "ui/events/mojo/event.mojom.h"
 #include "ui/views/mus/screen_mus.h"
 
@@ -230,6 +232,33 @@ void WindowManager::OnWmNewDisplay(::mus::Window* window,
   CreateRootWindowController(window, display);
 }
 
+void WindowManager::OnWmPerformMoveLoop(
+    ::mus::Window* window,
+    ::mus::mojom::MoveLoopSource source,
+    const gfx::Point& cursor_location,
+    const base::Callback<void(bool)>& on_done) {
+  WmWindowMus* child_window = WmWindowMus::Get(window);
+  MoveEventHandler* handler = MoveEventHandler::GetForWindow(child_window);
+  if (!handler) {
+    on_done.Run(false);
+    return;
+  }
+
+  DCHECK(!handler->IsDragInProgress());
+  aura::client::WindowMoveSource aura_source =
+      source == ::mus::mojom::MoveLoopSource::MOUSE
+          ? aura::client::WINDOW_MOVE_SOURCE_MOUSE
+          : aura::client::WINDOW_MOVE_SOURCE_TOUCH;
+  handler->AttemptToStartDrag(cursor_location, HTCAPTION, aura_source, on_done);
+}
+
+void WindowManager::OnWmCancelMoveLoop(::mus::Window* window) {
+  WmWindowMus* child_window = WmWindowMus::Get(window);
+  MoveEventHandler* handler = MoveEventHandler::GetForWindow(child_window);
+  if (handler)
+    handler->RevertDrag();
+}
+
 void WindowManager::OnAccelerator(uint32_t id, const ui::Event& event) {
   switch (id) {
     case kWindowSwitchAccelerator:
@@ -242,17 +271,5 @@ void WindowManager::OnAccelerator(uint32_t id, const ui::Event& event) {
   }
 }
 
-void WindowManager::OnWmPerformMoveLoop(
-    ::mus::Window* window,
-    ::mus::mojom::MoveLoopSource source,
-    const gfx::Point& cursor_location,
-    const base::Callback<void(bool)>& on_done) {
-  NOTIMPLEMENTED();
-}
-
-void WindowManager::OnWmCancelMoveLoop(::mus::Window* window) {
-  NOTIMPLEMENTED();
-}
-
 }  // namespace mus
 }  // namespace ash