Adds initial classes for DwaReportingService

Adds the DwaReportingService class and classes it requires.
This code will be used by de-identified web analytics metrics service.

Bug: 349452263
Change-Id: I169ef4667801c486cd3906ec6f8b7f945a53a483
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5873884
Code-Coverage: [email protected] <[email protected]>
Reviewed-by: Luc Nguyen <[email protected]>
Commit-Queue: Jay Zhou <[email protected]>
Reviewed-by: Zainab Rizvi <[email protected]>
Reviewed-by: Rohit Rao <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1360094}
diff --git a/components/metrics/metrics_log_uploader.h b/components/metrics/metrics_log_uploader.h
index 6b07dde..01df850 100644
--- a/components/metrics/metrics_log_uploader.h
+++ b/components/metrics/metrics_log_uploader.h
@@ -39,6 +39,7 @@
     UMA,
     UKM,
     STRUCTURED_METRICS,
+    DWA,
   };
 
   virtual ~MetricsLogUploader() = default;