[Sync] Avoid sending the processor metadata again on re-enabling sync.

components/sync/device_info/device_info_service_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/sync/device_info/device_info_service.h"
 
 #include <algorithm>
 #include <set>
 #include <utility>
 
@@ skipping 320 matching lines @@
   local_device()->Initialize(CreateDeviceInfo());
   base::RunLoop().RunUntilIdle();
 
   DeviceInfoList devices = service()->GetAllDeviceInfo();
   ASSERT_EQ(1u, devices.size());
   ASSERT_TRUE(local_device()->GetLocalDeviceInfo()->Equals(*devices[0]));
 }
 
 // Metadata shouldn't be loaded before the provider is initialized.
 TEST_F(DeviceInfoServiceTest, LocalProviderInitRace) {
-  set_local_device(base::WrapUnique(new LocalDeviceInfoProviderMock()));
+  set_local_device(base::MakeUnique<LocalDeviceInfoProviderMock>());
   InitializeAndPump();
   EXPECT_FALSE(processor()->metadata());
 
   ASSERT_EQ(0u, service()->GetAllDeviceInfo().size());
   local_device()->Initialize(CreateDeviceInfo());
   base::RunLoop().RunUntilIdle();
 
   DeviceInfoList devices = service()->GetAllDeviceInfo();
   ASSERT_EQ(1u, devices.size());
   ASSERT_TRUE(local_device()->GetLocalDeviceInfo()->Equals(*devices[0]));
@@ skipping 372 matching lines @@
   EXPECT_EQ(1, service()->CountActiveDevices());
 
   change_list.clear();
   specifics.set_cache_guid("non-local");
   PushBackEntityChangeAdd(specifics, &change_list);
   service()->ApplySyncChanges(service()->CreateMetadataChangeList(),
                               change_list);
   EXPECT_EQ(2, service()->CountActiveDevices());
 }
 
+TEST_F(DeviceInfoServiceTest, MultipleOnProviderInitialized) {
+  set_local_device(base::MakeUnique<LocalDeviceInfoProviderMock>());
+  InitializeAndPump();
+  EXPECT_EQ(nullptr, processor()->metadata());
+
+  // Verify the processor was given metadata.
+  local_device()->Initialize(CreateDeviceInfo());
+  base::RunLoop().RunUntilIdle();
+  const MetadataBatch* metadata = processor()->metadata();
+  EXPECT_NE(nullptr, metadata);
+
+  // Pointer address of metadata should remain constant because the processor
+  // should not have been given new metadata.
+  local_device()->Initialize(CreateDeviceInfo());
+  base::RunLoop().RunUntilIdle();
+  EXPECT_EQ(metadata, processor()->metadata());
+}
+
 }  // namespace
 
 }  // namespace syncer