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 2da1f80db5b6d240f2d0b316c1fe773471810161..232aa1a26b6613e5460c4cdf5932cb7624ea854b 100644
--- a/ui/views/controls/scrollbar/base_scroll_bar.cc
+++ b/ui/views/controls/scrollbar/base_scroll_bar.cc
@@ -415,6 +415,13 @@ 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();
 }