MacViews: Implement Tab Dragging

chrome/browser/ui/views/tabs/tab_drag_controller.cc

Index: chrome/browser/ui/views/tabs/tab_drag_controller.cc
diff --git a/chrome/browser/ui/views/tabs/tab_drag_controller.cc b/chrome/browser/ui/views/tabs/tab_drag_controller.cc
index cc8e272a46a9d2ff07d447a846d00f41465985a5..1cb5ce2b4fb98031a347b212f798c7b658cfd76b 100644
--- a/chrome/browser/ui/views/tabs/tab_drag_controller.cc
+++ b/chrome/browser/ui/views/tabs/tab_drag_controller.cc
@@ -382,7 +382,10 @@ void TabDragController::Drag(const gfx::Point& point_in_screen) {
                                          &drag_bounds);
         widget->SetVisibilityChangedAnimationsEnabled(true);
       }
-      RunMoveLoop(GetWindowOffset(point_in_screen));
+      // Use the start point to initialize the move loop, otherwise the point
+      // under the cursor will be offset by the drag threshold from where the
+      // user originally clicked, which could be entirely off the window.
+      RunMoveLoop(GetWindowOffset(start_point_in_screen_));
       return;
     }
   }