[Mac] Avoid "adding unknown subview" warning.

chrome/browser/ui/cocoa/tabs/tab_strip_view.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "chrome/browser/ui/cocoa/tabs/tab_strip_view.h"
 
 #include <cmath>  // floor
 
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
 #include "base/mac/mac_util.h"
 #include "base/mac/sdk_forward_declarations.h"
 #include "chrome/browser/themes/theme_properties.h"
 #include "chrome/browser/themes/theme_service.h"
 #import "chrome/browser/ui/cocoa/browser_window_controller.h"
+#import "chrome/browser/ui/cocoa/browser_window_layout.h"
 #import "chrome/browser/ui/cocoa/new_tab_button.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_strip_controller.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_view.h"
 #import "chrome/browser/ui/cocoa/view_id_util.h"
 #include "chrome/grit/generated_resources.h"
 #include "chrome/grit/theme_resources.h"
 #import "ui/base/cocoa/appkit_utils.h"
 #import "ui/base/cocoa/nsgraphics_context_additions.h"
 #import "ui/base/cocoa/nsview_additions.h"
 #include "ui/base/l10n/l10n_util_mac.h"
@@ skipping 318 matching lines @@
 
 - (void)setNewTabButton:(NewTabButton*)button {
   newTabButton_.reset([button retain]);
 }
 
 - (NSVisualEffectView*)visualEffectView {
   // NSVisualEffectView is only available on OS X 10.10 and higher.
   if (!base::mac::IsAtLeastOS10_10())
     return nil;
 
-  NSView* rootView = [[[self window] contentView] superview];
+  NSView* rootView = [[self window] contentView];
+  if (!chrome::ShouldUseFullSizeContentView()) {
+    rootView = [rootView superview];
+  }
+
   Class nsVisualEffectViewClass = NSClassFromString(@"NSVisualEffectView");
   DCHECK(nsVisualEffectViewClass);
   for (NSView* view in [rootView subviews]) {
     if ([view isKindOfClass:nsVisualEffectViewClass]) {
       return base::mac::ObjCCast<NSVisualEffectView>(view);
     }
   }
   return nil;
 }
 
@@ skipping 52 matching lines @@
   if (visualEffectsDisabledForFullscreen_ ||
       themeProvider->HasCustomImage(IDR_THEME_FRAME) ||
       themeProvider->HasCustomColor(ThemeProperties::COLOR_FRAME)) {
     [visualEffectView setState:NSVisualEffectStateInactive];
   } else {
     [visualEffectView setState:NSVisualEffectStateFollowsWindowActiveState];
   }
 }
 
 @end