Headless: enable disk cache for default profile

Start using disk cache directory for default headless profile.

Bug: 882431
Change-Id: I1790a58fa2da6cb0fd114897d082e289d7a01bc5
Reviewed-on: https://chromium-review.googlesource.com/c/1350881Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Commit-Queue: Andrey Lushnikov <lushnikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611230}

headless/lib/browser/headless_request_context_manager.cc

@@ -415,6 +415,8 @@ HeadlessRequestContextManager::CreateNetworkContextParams() {
         user_data_path_.Append(FILE_PATH_LITERAL("Cookies"));
     context_params->channel_id_path =
         user_data_path_.Append(FILE_PATH_LITERAL("Origin Bound Certs"));
+    context_params->http_cache_path =
+        user_data_path_.Append(FILE_PATH_LITERAL("Cache"));
   }
   if (proxy_config_) {
     context_params->initial_proxy_config = net::ProxyConfigWithAnnotation(