Implement GetSandboxType() on all platforms and implement for all process types.

content/public/browser/content_browser_client.cc

 // 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.
 
 #include "content/public/browser/content_browser_client.h"
 
 #include "base/files/file_path.h"
 #include "content/public/browser/client_certificate_delegate.h"
 #include "ui/gfx/image/image_skia.h"
 #include "url/gurl.h"
@@ skipping 317 matching lines @@
     content::BrowserContext* browser_context,
     const content::OpenURLParams& params,
     const base::Callback<void(content::WebContents*)>& callback) {
   callback.Run(nullptr);
 }
 
 #if defined(OS_WIN)
 const wchar_t* ContentBrowserClient::GetResourceDllName() {
   return nullptr;
 }
+
+base::string16 ContentBrowserClient::GetAppContainerSidForSandboxType(
+    int sandbox_type) const {
+  return base::string16();
+}
 #endif
 
 #if defined(VIDEO_HOLE)
 ExternalVideoSurfaceContainer*
 ContentBrowserClient::OverrideCreateExternalVideoSurfaceContainer(
     WebContents* web_contents) {
   NOTREACHED() << "Hole-punching is not supported. See crbug.com/469348.";
   return nullptr;
 }
 #endif
 
 }  // namespace content