[Sync] Added some basic extension sync integration tests.

chrome/browser/extensions/extension_updater.cc

Index: chrome/browser/extensions/extension_updater.cc
diff --git a/chrome/browser/extensions/extension_updater.cc b/chrome/browser/extensions/extension_updater.cc
index b2b3972451c4816fcfe85a7f7c91797461c2aeaa..654d6dc8c385eb7e70283b35782fcef1e70fad8d 100644
--- a/chrome/browser/extensions/extension_updater.cc
+++ b/chrome/browser/extensions/extension_updater.cc
@@ -417,6 +417,7 @@ void ExtensionUpdater::Start() {
 }
 
 void ExtensionUpdater::Stop() {
+  service_ = NULL;
   timer_.Stop();
   manifest_fetcher_.reset();
   extension_fetcher_.reset();
@@ -428,6 +429,10 @@ void ExtensionUpdater::OnURLFetchComplete(
     const URLFetcher* source, const GURL& url, const URLRequestStatus& status,
     int response_code, const ResponseCookies& cookies,
     const std::string& data) {
+  // This can be called after we've been stopped.
+  if (!service_)
+    return;
+
   if (source == manifest_fetcher_.get()) {
     OnManifestFetchComplete(url, status, response_code, data);
   } else if (source == extension_fetcher_.get()) {
@@ -540,6 +545,9 @@ void ExtensionUpdater::OnManifestFetchComplete(const GURL& url,
 void ExtensionUpdater::HandleManifestResults(
     const ManifestFetchData& fetch_data,
     const UpdateManifest::Results& results) {
+  // This can be called after we've been stopped.
+  if (!service_)
+    return;
 
   // Examine the parsed manifest and kick off fetches of any new crx files.
   std::vector<int> updates = DetermineUpdates(fetch_data, results);