Give the browser window's content view a CALayers

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 043ac8f4b09baeb4db6e407591eee35b18feda86..17dbea8fe67926df289225bb531774d5ae7dfc4d 100644
--- a/chrome/browser/ui/cocoa/browser_window_controller.mm
+++ b/chrome/browser/ui/cocoa/browser_window_controller.mm
@@ -262,6 +262,10 @@ enum {
     browser_.reset(browser);
     ownsBrowser_ = ownIt;
     NSWindow* window = [self window];
+    // Make the content view for the window have a layer. This will make all
+    // sub-views have layers. This is necessary to ensure correct layer
+    // ordering of all child views and their layers.
+    [[window contentView] cr_setWantsLayer:YES];
     windowShim_.reset(new BrowserWindowCocoa(browser, self));
 
     // Set different minimum sizes on tabbed windows vs non-tabbed, e.g. popups.