Add custom owners for v8_unwinder*

Top level Chrome owners don't have good insight into this code.
Delegate ownership to the profiler owners.

Change-Id: Ic64be4bbac1cea90af8cabbecb085aa1e1c1905b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2499174Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Mike Wittman <wittman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821726}

chrome/renderer/OWNERS

@@ -4,9 +4,13 @@ per-file BUILD.gn=*
 
 # Page Load Histogram files.
 per-file loadtimes_extension_bindings*=file://components/page_load_metrics/OWNERS
+
 # Instant/Search files.
 per-file instant_restricted_id_cache*=file://chrome/browser/search/OWNERS
 
+# V8 unwinder files.
+per-file v8_unwinder*=file://base/profiler/OWNERS
+
 # For security review.
 per-file browser_exposed_renderer_interfaces.cc=set noparent
 per-file browser_exposed_renderer_interfaces.cc=file://ipc/SECURITY_OWNERS