MacViews: Implement Tab Dragging

ui/views/widget/native_widget_mac.mm

Index: ui/views/widget/native_widget_mac.mm
diff --git a/ui/views/widget/native_widget_mac.mm b/ui/views/widget/native_widget_mac.mm
index 96580ce57ff6330ac0b88f486e9f0f089929394c..8050abe94f08fe16982cf983f44e2b62c248ab7b 100644
--- a/ui/views/widget/native_widget_mac.mm
+++ b/ui/views/widget/native_widget_mac.mm
@@ -551,12 +551,15 @@ Widget::MoveLoopResult NativeWidgetMac::RunMoveLoop(
     const gfx::Vector2d& drag_offset,
     Widget::MoveLoopSource source,
     Widget::MoveLoopEscapeBehavior escape_behavior) {
-  NOTIMPLEMENTED();
-  return Widget::MOVE_LOOP_CANCELED;
+  if (!bridge_)
+    return Widget::MOVE_LOOP_CANCELED;
+
+  return bridge_->RunMoveLoop(drag_offset);
 }
 
 void NativeWidgetMac::EndMoveLoop() {
-  NOTIMPLEMENTED();
+  if (bridge_)
+    bridge_->EndMoveLoop();
 }
 
 void NativeWidgetMac::SetVisibilityChangedAnimationsEnabled(bool value) {