Remove WebRequestEventDetails unused typedef

This base::Callback typedef isn't actually used anywhere so remove it.

Bug: 1152268
Change-Id: I07a9664c22622d77de5b746a102e1dceeedf9016
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2605351Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
Commit-Queue: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840356}

extensions/browser/api/web_request/web_request_event_details.h

@@ -42,9 +42,6 @@ struct WebRequestInfo;
 // other threads, as long as there is no concurrent access.
 class WebRequestEventDetails {
  public:
-  using DeterminedFrameDataCallback =
-      base::Callback<void(std::unique_ptr<WebRequestEventDetails>)>;
-
   // Create a WebRequestEventDetails with the following keys:
   // - method
   // - requestId