ambient: Clean up one comment

Change-Id: I2928f064f9948975d4b54e25d461ebefbbecf924
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2367114Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Commit-Queue: Tao Wu <wutao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800187}

ash/ambient/ambient_access_token_controller.cc

@@ -110,7 +110,6 @@ void AmbientAccessTokenController::NotifyAccessTokenRefreshed() {
 }
 
 void AmbientAccessTokenController::RunCallback(AccessTokenCallback callback) {
-  LOG(ERROR) << " DW run calback " << access_token_;
   std::move(callback).Run(gaia_id_, access_token_);
 }