Don't DCHECK in AttachmentServiceProxyForTest when MessageLoop is absent

The code in AttachmentServiceProxyForTest::Create checks that
base::ThreadTaskRunnerHandle::Get() returns valid runner in the
incorrect way. Get() DCHECKs that there is valid MessageLoop.
Instead it should check ThreadTaskRunnerHandle::IsSet().

BUG=449327
R=maniscalco@chromium.org

Review URL: https://codereview.chromium.org/814273006

Cr-Commit-Position: refs/heads/master@{#311917}

2 files changed, 19 insertions, 9 deletions

diff --git a/sync/api/attachments/attachment_store.cc b/sync/api/attachments/attachment_store.cc
index 9b22c51..129ac0b5 100644
--- a/sync/api/attachments/attachment_store.cc
+++ b/sync/api/attachments/attachment_store.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/location.h"
+#include "base/message_loop/message_loop.h"
 #include "base/sequenced_task_runner.h"
 #include "base/thread_task_runner_handle.h"
 #include "sync/internal_api/public/attachments/attachment_store_handle.h"
@@ -23,10 +24,18 @@ AttachmentStore::~AttachmentStore() {}
 
 scoped_refptr<AttachmentStore> AttachmentStore::CreateInMemoryStore() {
   // Both frontend and backend of attachment store will live on current thread.
-  scoped_ptr<AttachmentStoreBase> backend(
-      new InMemoryAttachmentStore(base::ThreadTaskRunnerHandle::Get()));
-  return scoped_refptr<AttachmentStore>(new AttachmentStoreHandle(
-      backend.Pass(), base::ThreadTaskRunnerHandle::Get()));
+  scoped_refptr<base::SingleThreadTaskRunner> runner;
+  if (base::ThreadTaskRunnerHandle::IsSet()) {
+    runner = base::ThreadTaskRunnerHandle::Get();
+  } else {
+    // Dummy runner for tests that don't have MessageLoop.
+    base::MessageLoop loop;
+    // This works because |runner| takes a ref to the proxy.
+    runner = base::ThreadTaskRunnerHandle::Get();
+  }
+  scoped_ptr<AttachmentStoreBase> backend(new InMemoryAttachmentStore(runner));
+  return scoped_refptr<AttachmentStore>(
+      new AttachmentStoreHandle(backend.Pass(), runner));
 }
 
 scoped_refptr<AttachmentStore> AttachmentStore::CreateOnDiskStore(
diff --git a/sync/internal_api/attachments/attachment_service_proxy_for_test.cc b/sync/internal_api/attachments/attachment_service_proxy_for_test.cc
index 53f7d60..8682a91 100644
--- a/sync/internal_api/attachments/attachment_service_proxy_for_test.cc
+++ b/sync/internal_api/attachments/attachment_service_proxy_for_test.cc
@@ -38,14 +38,15 @@ AttachmentServiceProxy AttachmentServiceProxyForTest::Create() {
   scoped_refptr<Core> core_for_test(
       new OwningCore(wrapped.Pass(), weak_ptr_factory.Pass()));
 
-  scoped_refptr<base::SequencedTaskRunner> runner(
-      base::ThreadTaskRunnerHandle::Get());
-  if (!runner.get()) {
-    // Dummy runner for tests that don't care about AttachmentServiceProxy.
+  scoped_refptr<base::SequencedTaskRunner> runner;
+  if (base::ThreadTaskRunnerHandle::IsSet()) {
+    runner = base::ThreadTaskRunnerHandle::Get();
+  } else {
+    // Dummy runner for tests that don't have MessageLoop.
     DVLOG(1) << "Creating dummy MessageLoop for AttachmentServiceProxy.";
     base::MessageLoop loop;
     // This works because |runner| takes a ref to the proxy.
-    runner = loop.message_loop_proxy();
+    runner = base::ThreadTaskRunnerHandle::Get();
   }
   return AttachmentServiceProxyForTest(runner, core_for_test);
 }