MacViews: Reveal scrollbars when resting on the trackpad.

ui/views/controls/scrollbar/base_scroll_bar.cc

Index: ui/views/controls/scrollbar/base_scroll_bar.cc
diff --git a/ui/views/controls/scrollbar/base_scroll_bar.cc b/ui/views/controls/scrollbar/base_scroll_bar.cc
index 82d852944b656dadf77f632a2663201039b3eb64..428ce5ff13013e954485ea3fff59dc41066cbcbc 100644
--- a/ui/views/controls/scrollbar/base_scroll_bar.cc
+++ b/ui/views/controls/scrollbar/base_scroll_bar.cc
@@ -440,6 +440,13 @@ int BaseScrollBar::GetScrollIncrement(bool is_page, bool is_positive) {
 ///////////////////////////////////////////////////////////////////////////////
 // BaseScrollBar, private:
 
+#if !defined(OS_MACOSX)
+// static
+base::Timer* BaseScrollBar::GetHideTimerForTest(BaseScrollBar* scroll_bar) {
+  return nullptr;
+}
+#endif
+
 int BaseScrollBar::GetThumbSizeForTest() {
   return thumb_->GetSize();
 }