Fix window activation issue.

BUG=913314

Change-Id: I01de2642638dde55945f41dfa58da41a30b2c095
Reviewed-on: https://chromium-review.googlesource.com/c/1435957
Auto-Submit: Avi Drissman <avi@chromium.org>
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#626117}

ui/views_bridge_mac/views_nswindow_delegate.mm

@@ -6,6 +6,7 @@
 
 #include "base/bind.h"
 #include "base/logging.h"
+#include "base/mac/mac_util.h"
 #include "base/threading/thread_task_runner_handle.h"
 #import "ui/views_bridge_mac/bridged_content_view.h"
 #include "ui/views_bridge_mac/bridged_native_widget_host_helper.h"
@@ -179,6 +180,17 @@
 }
 
 - (void)windowDidExitFullScreen:(NSNotification*)notification {
+  if (base::mac::IsOS10_12()) {
+    // There is a window activation/fullscreen bug present only in macOS 10.12
+    // that might cause a security surface to appear over the wrong parent
+    // window. As much as this code appears to be a no-op, it is not; it causes
+    // AppKit to shuffle all the windows around to properly obey the
+    // relationships that they should already be obeying.
+    [[NSApp orderedWindows][0] performSelector:@selector(orderFront:)
+                                    withObject:self
+                                    afterDelay:0];
+  }
+
   parent_->OnFullscreenTransitionComplete(false);
 }