PVer4: Test checksum on startup outside the hotpath of DB load

components/safe_browsing_db/v4_local_database_manager_unittest.cc

Index: components/safe_browsing_db/v4_local_database_manager_unittest.cc
diff --git a/components/safe_browsing_db/v4_local_database_manager_unittest.cc b/components/safe_browsing_db/v4_local_database_manager_unittest.cc
index d3e75cb3b46b559a79ea2fead54e8768ee5899d0..eb1042ce589aa8bc4980477ecf5a21b58ec3c1ee 100644
--- a/components/safe_browsing_db/v4_local_database_manager_unittest.cc
+++ b/components/safe_browsing_db/v4_local_database_manager_unittest.cc
@@ -82,11 +82,21 @@ class V4LocalDatabaseManagerTest : public PlatformTest {
   }
 
   void ReplaceV4Database(const StoreAndHashPrefixes& store_and_hash_prefixes) {
+    // Make sure that VerifyChecksum runs before we reset.
+    task_runner_->RunPendingTasks();
+    base::RunLoop().RunUntilIdle();
+
     v4_local_database_manager_->v4_database_.reset(new FakeV4Database(
         task_runner_, base::MakeUnique<StoreMap>(), store_and_hash_prefixes));
   }
 
-  void ResetV4Database() { v4_local_database_manager_->v4_database_.reset(); }
+  void ResetV4Database() {
+    // Make sure that VerifyChecksum runs before we reset.
+    task_runner_->RunPendingTasks();
+    base::RunLoop().RunUntilIdle();
+
+    v4_local_database_manager_->v4_database_.reset();
+  }
 
   void StartLocalDatabaseManager() {
     v4_local_database_manager_->StartOnIOThread(NULL, V4ProtocolConfig());