[Merge M60] Fix shelf dragging context in case Context Menu is shown.

ash/shelf/shelf_button.cc

Index: ash/shelf/shelf_button.cc
diff --git a/ash/shelf/shelf_button.cc b/ash/shelf/shelf_button.cc
index 53cf800bbb5e92de9455233308ccf9c3be89871c..d9fa9a4f67dadd8d30abce42528da1b051db9836 100644
--- a/ash/shelf/shelf_button.cc
+++ b/ash/shelf/shelf_button.cc
@@ -315,8 +315,12 @@ void ShelfButton::ShowContextMenu(const gfx::Point& p,
     destroyed_flag_ = nullptr;
     // The menu will not propagate mouse events while its shown. To address,
     // the hover state gets cleared once the menu was shown (and this was not
-    // destroyed).
-    ClearState(STATE_HOVERED);
+    // destroyed). In case context menu is shown target view does not receive
+    // OnMouseReleased events and we need to cancel capture manually.
+    if (shelf_view_->drag_view() == this)
+      OnMouseCaptureLost();
+    else
+      ClearState(STATE_HOVERED);
   }
 }