Adding sophiechang@ to previews owners.

Change-Id: I8b484bd4d68c72adc5ef453f2a8e0969aeb5eea6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1815577
Auto-Submit: Michael Crouse <mcrouse@chromium.org>
Reviewed-by: Sophie Chang <sophiechang@chromium.org>
Commit-Queue: Robert Ogden <robertogden@chromium.org>
Cr-Commit-Position: refs/heads/master@{#698676}

components/data_reduction_proxy/OWNERS

@@ -6,6 +6,7 @@ rajendrant@chromium.org
 robertogden@chromium.org
 ryansturm@chromium.org
 sclittle@chromium.org
+sophiechang@chromium.org
 
 # Secondary
 bengr@chromium.org