Add extensions code to use common updater in components/update_client/

extensions/browser/extensions_browser_client.cc

Index: extensions/browser/extensions_browser_client.cc
diff --git a/extensions/browser/extensions_browser_client.cc b/extensions/browser/extensions_browser_client.cc
index 495ac50c0da403b79512358fda81fe135b58829c..d113f1189788f5574feebd268ef37581dbb508ca 100644
--- a/extensions/browser/extensions_browser_client.cc
+++ b/extensions/browser/extensions_browser_client.cc
@@ -6,7 +6,9 @@
 
 #include "base/basictypes.h"
 #include "base/logging.h"
+#include "components/update_client/update_client.h"
 #include "extensions/browser/extension_error.h"
+#include "extensions/browser/updater/update_client_config.h"
 
 namespace extensions {
 
@@ -16,6 +18,11 @@ ExtensionsBrowserClient* g_client = NULL;
 
 }  // namespace
 
+scoped_refptr<update_client::UpdateClient>
+ExtensionsBrowserClient::CreateUpdateClient(content::BrowserContext* context) {
+  return scoped_refptr<update_client::UpdateClient>(nullptr);
+}
+
 void ExtensionsBrowserClient::ReportError(content::BrowserContext* context,
                                           scoped_ptr<ExtensionError> error) {
   LOG(ERROR) << error->GetDebugString();