First step in enabling creating tabs without an Activity on Android.

content/shell/browser/shell_content_browser_client.cc

 // Copyright 2013 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/shell/browser/shell_content_browser_client.h"
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/files/file.h"
 #include "base/files/file_util.h"
@@ skipping 285 matching lines @@
     const GURL& current_url,
     const GURL& new_url) {
   return g_swap_processes_for_redirect;
 }
 
 DevToolsManagerDelegate*
 ShellContentBrowserClient::GetDevToolsManagerDelegate() {
   return new ShellDevToolsManagerDelegate(browser_context());
 }
 
-WebContents* ShellContentBrowserClient::OpenURL(BrowserContext* browser_context,
-                                                const OpenURLParams& params) {
-  return Shell::CreateNewWindow(browser_context,
-                                params.url,
-                                nullptr,
-                                gfx::Size())->web_contents();
+void ShellContentBrowserClient::OpenURL(
+    BrowserContext* browser_context,
+    const OpenURLParams& params,
+    const base::Callback<void(WebContents*)>& callback) {
+  callback.Run(Shell::CreateNewWindow(browser_context,
+                                      params.url,
+                                      nullptr,
+                                      gfx::Size())->web_contents());
 }
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
 void ShellContentBrowserClient::GetAdditionalMappedFilesForChildProcess(
     const base::CommandLine& command_line,
     int child_process_id,
     FileDescriptorInfo* mappings) {
 #if defined(OS_ANDROID)
   int flags = base::File::FLAG_OPEN | base::File::FLAG_READ;
   base::FilePath pak_file;
@@ skipping 62 matching lines @@
 ShellBrowserContext*
 ShellContentBrowserClient::ShellBrowserContextForBrowserContext(
     BrowserContext* content_browser_context) {
   if (content_browser_context == browser_context())
     return browser_context();
   DCHECK_EQ(content_browser_context, off_the_record_browser_context());
   return off_the_record_browser_context();
 }
 
 }  // namespace content