Set AllowOverlappingViews for history overlay

chrome/browser/ui/cocoa/browser_window_controller.mm

Index: chrome/browser/ui/cocoa/browser_window_controller.mm
diff --git a/chrome/browser/ui/cocoa/browser_window_controller.mm b/chrome/browser/ui/cocoa/browser_window_controller.mm
index 9c637694dab9e74dfe3286c27a0f4d2cbed505b8..1dc4ce8dd0f85b75c7da7643a568e71da250d6ed 100644
--- a/chrome/browser/ui/cocoa/browser_window_controller.mm
+++ b/chrome/browser/ui/cocoa/browser_window_controller.mm
@@ -1992,6 +1992,16 @@ willAnimateFromState:(BookmarkBar::State)oldState
   [self updateAllowOverlappingViews:[self inPresentationMode]];
 }
 
+- (void)onHistoryOverlayShown {
+  ++historyOverlayCount_;

[Robert Sesek, 2013/06/10 20:30:35]

Why do we need to count them?

[sail, 2013/06/10 20:56:01]

The window controller instance is referenced by multiple RWHVs. In practice
there won't be more than one though. I can make this a BOOL with a DCHECK if you
like.

[Robert Sesek, 2013/06/10 20:59:28]

I guess it depends on what the invariant is. It seems odd to count if it only
ever goes to 1.

[sail, 2013/06/10 22:21:07]

I verified that the count can be greater than 1. For example:
 - swipe to go back
 - immediately swipe to go forward
Because there's a delay before the overlay is hidden you can have two overlays
at the same time.

I believe you can also reproduce this with multiple tabs.

+  [self updateAllowOverlappingViews:[self inPresentationMode]];
+}
+
+- (void)onHistoryOverlayHidden {
+  --historyOverlayCount_;
+  [self updateAllowOverlappingViews:[self inPresentationMode]];
+}
+
 @end  // @implementation BrowserWindowController