[CrOS MultiDevice] Fix two bugs related to removing the host device.

(1) HostVerifierImpl::IsHostVerified() returned true if the device had
    previously been verified but was pending removal. If a device is
    pending removal, the user has explicitly requested that it be
    removed as the host device, so it should not be considered verified.
(2) RemoteDeviceCache::SetRemoteDevices() skipped overwriting device
    metadata if that data was not newer than the previously-stored data.
    However, there is currently a bug on the CryptAuth back-end which
    does not update the device metadata update time when a feature has
    been changed from supported to enabled or vice versa. Thus, this
    check has been temporarily removed until the back-end bug has been
    fixed.

Bug: 870069, 824568
Change-Id: Ie748e5d662a9ea00cf1b5e6a42fc8354c986d61e
Reviewed-on: https://chromium-review.googlesource.com/1192417Reviewed-by: James Hawkins <jhawkins@chromium.org>
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586767}

chromeos/services/multidevice_setup/host_verifier_impl.cc

@@ -113,6 +113,13 @@ bool HostVerifierImpl::IsHostVerified() {
   if (!current_host)
     return false;
 
+  // If a host exists on the back-end but there is a pending request to remove
+  // that host, the device pending removal is no longer considered verified.
+  if (host_backend_delegate_->HasPendingHostRequest() &&
+      !host_backend_delegate_->GetPendingHostRequest()) {
+    return false;
+  }
+
   // If one or more potential host sofware features is enabled, the host is
   // considered verified.
   for (const auto& software_feature : kPotentialHostFeatures) {

chromeos/services/multidevice_setup/host_verifier_impl_unittest.cc

@@ -134,6 +134,10 @@ class MultiDeviceSetupHostVerifierImplTest : public testing::Test {
       mock_timer_->Fire();
   }
 
+  FakeHostBackendDelegate* fake_host_backend_delegate() {
+    return fake_host_backend_delegate_.get();
+  }
+
  private:
   cryptauth::RemoteDeviceRef test_device_;
 
@@ -312,6 +316,22 @@ TEST_F(MultiDeviceSetupHostVerifierImplTest,
       kFirstRetryDeltaMs /* expected_retry_delta_value */);
 }
 
+TEST_F(MultiDeviceSetupHostVerifierImplTest,
+       StartWithVerifiedHost_PendingRemoval) {
+  CreateVerifier(HostState::kHostVerified);
+  VerifyState(true /* expected_is_verified */,
+              0u /* expected_num_verified_events */,
+              0 /* expected_retry_timestamp_value */,
+              0 /* expected_retry_delta_value */);
+
+  fake_host_backend_delegate()->AttemptToSetMultiDeviceHostOnBackend(
+      base::nullopt /* host_device */);
+  VerifyState(false /* expected_is_verified */,
+              0u /* expected_num_verified_events */,
+              0 /* expected_retry_timestamp_value */,
+              0 /* expected_retry_delta_value */);
+}
+
 }  // namespace multidevice_setup
 
 }  // namespace chromeos

components/cryptauth/remote_device_cache.cc

@@ -41,13 +41,8 @@ void RemoteDeviceCache::SetRemoteDevices(
     const RemoteDeviceList& remote_devices) {
   for (const auto& remote_device : remote_devices) {
     if (base::ContainsKey(remote_device_map_, remote_device.GetDeviceId())) {
-      // Skip if the incoming remote device object contains
-      // a stale timestamp.
-      if (remote_device.last_update_time_millis <=
-          remote_device_map_[remote_device.GetDeviceId()]
-              ->last_update_time_millis) {
-        continue;
-      }
+      // TODO(khorimoto): Do not overwrite device metadata if the new device
+      // contains a stale timestamp; see https://crbug.com/856746.
 
       // Keep the same shared_ptr object, and simply
       // update the RemoteDevice it references. This transparently updates

components/cryptauth/remote_device_cache_unittest.cc

@@ -87,9 +87,11 @@ TEST_F(RemoteDeviceCacheTest,
   EXPECT_EQ(remote_device.name, remote_device_ref.name());
 }
 
+// Currently disabled; will be re-enabled when https://crbug.com/856746 is
+// fixed.
 TEST_F(
     RemoteDeviceCacheTest,
-    TestSetRemoteDevices_RemoteDeviceCacheDoesNotUpdateWithStaleRemoteDevice) {
+    DISABLED_TestSetRemoteDevices_RemoteDeviceCacheDoesNotUpdateWithStaleRemoteDevice) {
   // Store the device with a last update time of 1000.
   cryptauth::RemoteDevice remote_device =
       cryptauth::CreateRemoteDeviceForTest();