[MacViews] Show combobox menu popup at mouse press

ui/views/controls/combobox/combobox.cc

Index: ui/views/controls/combobox/combobox.cc
diff --git a/ui/views/controls/combobox/combobox.cc b/ui/views/controls/combobox/combobox.cc
index 3d7cfd1e26585dae22ab9fd8f8cfe5d876987304..aa7d0b5fe3d07d4126907af15f33f54855bf9ce5 100644
--- a/ui/views/controls/combobox/combobox.cc
+++ b/ui/views/controls/combobox/combobox.cc
@@ -110,13 +110,19 @@ class TransparentButton : public CustomButton {
       : CustomButton(listener) {
     SetAnimationDuration(LabelButton::kHoverAnimationDurationMs);
     SetFocusBehavior(FocusBehavior::NEVER);
+    set_notify_action(PlatformStyle::kMenuActivationAction);
   }
   ~TransparentButton() override {}
 
+#if defined(OS_MACOSX)

[sky, 2016/06/29 21:35:08]

This ifdef means we'll no longer get the old behavior on non-macos. Also, for
mac, are you sure you want to change focus at all?

[tapted, 2016/06/29 23:24:43]

oh! yeah - this #ifdef needs to be inverted. (somehow I always saw an extra '!'
here already :/).

+  // Override OnMousePressed() to transfer focus to the parent() on a click
+  // except on Mac, which doesn't transfer focus when buttons are clicked.
   bool OnMousePressed(const ui::MouseEvent& mouse_event) override {
     parent()->RequestFocus();
+    CustomButton::OnMousePressed(mouse_event);
     return true;
   }
+#endif
 
   double GetAnimationValue() const {
     return hover_animation().GetCurrentValue();