[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..787a72504974e92bd59feb47ad8cc6bb4873f368 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)
+  // Override OnMousePressed() to transfer focus on the parent() on a click

[tapted, 2016/06/29 12:02:55]

"on the parent() on a click" -> "to the parent() on a click."
"on Mac," -> "Except on Mac,"

[spqchan, 2016/06/29 18:29:14]

Done.

+  // 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);

[tapted, 2016/06/29 12:02:55]

nit: remove this bit (although I think it's fine, there's no longer a reason to
make this change and there could be something subtle).

[spqchan, 2016/06/29 18:29:14]

We need this actually because CustomButton::MousePressed calls NotifyClick()

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

Ah! So, I think we can remove this once the #ifdef is inverted :).

     return true;
   }
+#endif
 
   double GetAnimationValue() const {
     return hover_animation().GetCurrentValue();