Add task runners to more tests

chrome/browser/autocomplete/in_memory_url_index_unittest.cc

Index: chrome/browser/autocomplete/in_memory_url_index_unittest.cc
diff --git a/chrome/browser/autocomplete/in_memory_url_index_unittest.cc b/chrome/browser/autocomplete/in_memory_url_index_unittest.cc
index 6aa02c0cc5d35f057592db609c9e6f2b87ac8502..5c68b4074e9bad4427cd9b4c86c10ffc85a2b8dc 100644
--- a/chrome/browser/autocomplete/in_memory_url_index_unittest.cc
+++ b/chrome/browser/autocomplete/in_memory_url_index_unittest.cc
@@ -1205,6 +1205,7 @@ class InMemoryURLIndexCacheTest : public testing::Test {
   void set_history_dir(const base::FilePath& dir_path);
   bool GetCacheFilePath(base::FilePath* file_path) const;
 
+  content::TestBrowserThreadBundle thread_bundle_;
   base::ScopedTempDir temp_dir_;
   scoped_ptr<InMemoryURLIndex> url_index_;
 };