android_webview: Add comment for exclusion of url in crash reports.

R=ericrk@chromium.org

Bug: 936575
Change-Id: I0265188debd9a94083272b4658b57994767bbc5f
Reviewed-on: https://chromium-review.googlesource.com/c/1492424
Commit-Queue: Tobias Sargeant <tobiasjs@chromium.org>
Reviewed-by: Eric Karl <ericrk@chromium.org>
Reviewed-by: Tobias Sargeant <tobiasjs@chromium.org>
Auto-Submit: Khushal <khushalsagar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636844}

components/viz/service/gl/gpu_service_impl.cc

@@ -624,6 +624,8 @@ void GpuServiceImpl::SendCreatedChildWindow(gpu::SurfaceHandle parent_window,
 
 void GpuServiceImpl::SetActiveURL(const GURL& url) {
   DCHECK(main_runner_->BelongsToCurrentThread());
+  // Note that the url is intentionally excluded from webview crash dumps
+  // using a whitelist for privacy reasons. See kWebViewCrashKeyWhiteList.
   static crash_reporter::CrashKeyString<1024> crash_key("url-chunk");
   crash_key.Set(url.possibly_invalid_spec());
 }