Mac: Fix window ordering for certificate viewer/selector sheets and overlays.

chrome/browser/ui/cocoa/certificate_viewer_mac_cocoa.mm

Index: chrome/browser/ui/cocoa/certificate_viewer_mac_cocoa.mm
diff --git a/chrome/browser/ui/cocoa/certificate_viewer_mac_cocoa.mm b/chrome/browser/ui/cocoa/certificate_viewer_mac_cocoa.mm
index 9fbc903727036debed4d069b0fd2de5d3dfab630..5714faf305f8dc09a00cb5d67553d91636a6f27a 100644
--- a/chrome/browser/ui/cocoa/certificate_viewer_mac_cocoa.mm
+++ b/chrome/browser/ui/cocoa/certificate_viewer_mac_cocoa.mm
@@ -99,6 +99,9 @@ class SSLCertificateViewerCocoaBridge : public ConstrainedWindowMacDelegate {
 
   oldResizesSubviews_ = [[sheetWindow contentView] autoresizesSubviews];
   [[sheetWindow contentView] setAutoresizesSubviews:NO];
+
+  // Ensure this overlay doesn't interfere with overlays with hidden sheets.
+  [overlayWindow_ setLevel:0];
 }
 
 - (void)unhideSheet {
@@ -107,6 +110,9 @@ class SSLCertificateViewerCocoaBridge : public ConstrainedWindowMacDelegate {
 
   [[sheetWindow contentView] setAutoresizesSubviews:oldResizesSubviews_];
   [[overlayWindow_ attachedSheet] setAlphaValue:1.0];
+
+  // Set the current overlay's level higher than overlays with hidden sheets.
+  [overlayWindow_ setLevel:1];
 }
 
 - (void)pulseSheet {