mac: Fix a history swiper bug where the shield wouldn't disappear.

chrome/browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper.mm

Index: chrome/browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper.mm
diff --git a/chrome/browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper.mm b/chrome/browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper.mm
index ac57d05d0939167fcbee940357c2764e7ba4b164..58f9e46b8590bad4b558c65f1d9da1c7172883bf 100644
--- a/chrome/browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper.mm
+++ b/chrome/browser/renderer_host/chrome_render_widget_host_view_mac_history_swiper.mm
@@ -246,7 +246,7 @@
                      ? kHistoryOverlayModeForward
                      : kHistoryOverlayModeBack];
   [historyOverlay showPanelForView:[delegate_ viewThatWantsHistoryOverlay]];
-  historyOverlay_ = [historyOverlay retain];

[Nico, 2013/12/28 00:08:30]

I guess this path isn't covered by tests, else asan should've found this, right?

[erikchen, 2013/12/30 19:20:34]

As far as I can tell, this path is covered by my mac_history_swiper_unit_test.
(There's a partial mock that still forwards of this method to the real object,
and I know that line 242 is called, because it broke unit tests when I added it.

According to llvm, LeakSanitizer is still in experimental mode, so I'm assuming
its stable, but doesn't catch all leaks...

+  historyOverlay_ = historyOverlay;
 
   // Record whether the user was swiping forwards or backwards.
   historySwipeDirection_ = direction;