Add sadrul@ to cc/OWNERS for metrics

sadrul@ is already reviewing a lot of metrics related code, this CL adds
him as an owner.

Bug: None
Change-Id: Ifc4fca00f9128f28c669f64116465087ead3b4a0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1769053Reviewed-by: enne <enne@chromium.org>
Commit-Queue: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#689993}

cc/OWNERS

@@ -51,6 +51,9 @@ bokan@chromium.org
 # scroll snap
 majidvp@chromium.org
 
+# metrics
+sadrul@chromium.org
+
 # general
 enne@chromium.org
 danakj@chromium.org