MacViews: Reveal scrollbars when resting on the trackpad.

ui/views/controls/scrollbar/base_scroll_bar.h

Index: ui/views/controls/scrollbar/base_scroll_bar.h
diff --git a/ui/views/controls/scrollbar/base_scroll_bar.h b/ui/views/controls/scrollbar/base_scroll_bar.h
index c8ede5bcb99e0621fdc64bf6848004fa67b46aa2..6018576967952db72031b2cd9b2e464db6879a14 100644
--- a/ui/views/controls/scrollbar/base_scroll_bar.h
+++ b/ui/views/controls/scrollbar/base_scroll_bar.h
@@ -116,6 +116,7 @@ class VIEWS_EXPORT BaseScrollBar : public ScrollBar,
 
   FRIEND_TEST_ALL_PREFIXES(ScrollBarViewsTest, ScrollBarFitsToBottom);
   FRIEND_TEST_ALL_PREFIXES(ScrollBarViewsTest, ThumbFullLengthOfTrack);
+  static base::Timer* GetHideTimerForTest(BaseScrollBar* scroll_bar);

[tapted, 2016/11/15 12:22:23]

(note: This is a bit of a trade-off. I didn't give cocoa_scroll_bar.h its own
test API since scroll_view_unittest.cc wouldn't be able to #include
cocoa_scroll_bar.h [because it's objective-C]. But if you don't like this I can
explore some options. E.g. I can move the #ifdef (MAC) unittests out to their
own, .mm. file [and make separate .h .cc for the current test api so both
_unittest.xx files can use it] - I think that will work.

There might also be a way to make cocoa_scroll_bar.h #includable in .cc files
with a bit of indirection.)

   int GetThumbSizeForTest();
 
   // Changes to 'pushed' state and starts a timer to scroll repeatedly.