Let IndexedDBContextImpl create its own task runner

content/browser/indexed_db/indexed_db_dispatcher_host_unittest.cc

Index: content/browser/indexed_db/indexed_db_dispatcher_host_unittest.cc
diff --git a/content/browser/indexed_db/indexed_db_dispatcher_host_unittest.cc b/content/browser/indexed_db/indexed_db_dispatcher_host_unittest.cc
index a73e010483e2c2093e5e66c9605207db1aeccded..9f27b8bb9199c40d992c039b0a5af5495d9f273c 100644
--- a/content/browser/indexed_db/indexed_db_dispatcher_host_unittest.cc
+++ b/content/browser/indexed_db/indexed_db_dispatcher_host_unittest.cc
@@ -148,8 +148,7 @@ class IndexedDBDispatcherHostTest : public testing::Test {
         context_impl_(
             new IndexedDBContextImpl(CreateAndReturnTempDir(&temp_dir_),
                                      special_storage_policy_.get(),
-                                     quota_manager_proxy_.get(),
-                                     idb_task_runner_.get())),
+                                     quota_manager_proxy_.get())),
         blob_storage_(ChromeBlobStorageContext::GetFor(&browser_context_)),
         host_(new IndexedDBDispatcherHost(kFakeProcessId,
                                           request_context_getter_.get(),
@@ -159,6 +158,7 @@ class IndexedDBDispatcherHostTest : public testing::Test {
                              kTemporaryQuota);
     quota_manager_->SetQuota(GURL(kOrigin), storage::kStorageTypeTemporary,
                              kPersistantQuota);
+    context_impl_->SetTaskRunnerForTesting(idb_task_runner_);
   }
 
   void TearDown() override {