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

content/shell/browser/shell_content_browser_client.cc

Index: content/shell/browser/shell_content_browser_client.cc
diff --git a/content/shell/browser/shell_content_browser_client.cc b/content/shell/browser/shell_content_browser_client.cc
index 9b8a2f458b86f6ab6db384a83f77d458644adae4..4f011e607d689f1d3b107935bcaa059eb3888ea9 100644
--- a/content/shell/browser/shell_content_browser_client.cc
+++ b/content/shell/browser/shell_content_browser_client.cc
@@ -303,12 +303,14 @@ 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)