Add dullweber@ as browsing_data extension owner

Change-Id: I5e4b63cb0a7bf86b4978b4089ab5fe9086d48a90
Reviewed-on: https://chromium-review.googlesource.com/c/1446351Reviewed-by: Mike West <mkwst@chromium.org>
Commit-Queue: Christian Dullweber <dullweber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#629961}

chrome/browser/extensions/api/browsing_data/OWNERS

 # Anyone in the parent directories can review changes to this directory,
 # but the following people are the most knowledgable:
+dullweber@chromium.org
 mkwst@chromium.org
 
 # COMPONENT: Platform>Extensions>API