Add conversion measurement component to conversions/OWNERS

Bug: 1045468
Change-Id: I5f581a84466270258186b9b4b2ddd73ce91970f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2036652Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Commit-Queue: John Delaney <johnidel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738198}

content/browser/conversions/OWNERS

@@ -2,4 +2,4 @@ csharrison@chromium.org
 johnidel@chromium.org
 
 # TEAM: privacy-sandbox-dev@chromium.org
-# TODO(https://crbug.com/1045468): Add a component for ConversionMeasurement.
+# COMPONENT: Internals>ConversionMeasurement