AU: remove obsolete proxy resolver code

The module chrome_proxy_resolver has been long obsoleted by
chrome_browser_proxy_resolver, only that it kept living in our codebase,
if only for the use of a single static method, which had nothing to do
with proxy resolution and in fact is Curl specific.  This CL removes it
along with its build/execution dependencies.

BUG=chromium:208655
TEST=Builds fine and unit tests running

Change-Id: Iff50c2c75451e5f3ddbc27c5a90a8b1a421a5d8d
Reviewed-on: https://gerrit.chromium.org/gerrit/63147
Tested-by: Gilad Arnold <garnold@chromium.org>
Reviewed-by: Alex Deymo <deymo@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Gilad Arnold <garnold@chromium.org>
diff --git a/libcurl_http_fetcher.h b/libcurl_http_fetcher.h
index 7dba810..07753a8 100644
--- a/libcurl_http_fetcher.h
+++ b/libcurl_http_fetcher.h
@@ -197,6 +197,11 @@
   // Sets the curl options for HTTPS URL.
   void SetCurlOptionsForHttps();
 
+  // Convert a proxy URL into a curl proxy type, if applicable. Returns true iff
+  // conversion was successful, false otherwise (in which case nothing is
+  // written to |out_type|).
+  bool GetProxyType(const std::string& proxy, curl_proxytype* out_type);
+
   // Handles for the libcurl library
   CURLM *curl_multi_handle_;
   CURL *curl_handle_;