Mac: Disconnect DesktopMediaPicker window from the parent before closing

The window wasn't removing itself from the parent's children list, which
causes linked bug with some versions of Cocoa.

BUG=331058

Review URL: https://codereview.chromium.org/125133006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243212 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/ui/cocoa/media_picker/desktop_media_picker_controller.mm

@@ -229,6 +229,10 @@ const int kExcessButtonPadding = 6;
   // Report the result if it hasn't been reported yet. |reportResult:| ensures
   // that the result is only reported once.
   [self reportResult:content::DesktopMediaID()];
+
+  // Remove self from the parent.
+  NSWindow* window = [self window];
+  [[window parentWindow] removeChildWindow:window];
 }
 
 #pragma mark IKImageBrowserDataSource