Do not handle the button click event for the mouse release of dragging launcher item.

ash/launcher/launcher_view.cc

Index: ash/launcher/launcher_view.cc
diff --git a/ash/launcher/launcher_view.cc b/ash/launcher/launcher_view.cc
index 62b98527f7ac8c6d4a42b48e04a268befbe8b581..2a99fcd9535b3393ca834b634cbbb0d1cbcb4dc6 100644
--- a/ash/launcher/launcher_view.cc
+++ b/ash/launcher/launcher_view.cc
@@ -694,6 +694,10 @@ string16 LauncherView::GetAccessibleName(const views::View* view) {
 
 void LauncherView::ButtonPressed(views::Button* sender,
                                  const views::Event& event) {
+  // Do not handle mouse release during drag.
+  if (dragging_)
+    return;
+
   if (sender == overflow_button_)
     ShowOverflowMenu();