Use a utility process for the Mojo v8 proxy resolver.

net/proxy/proxy_service.cc

Index: net/proxy/proxy_service.cc
diff --git a/net/proxy/proxy_service.cc b/net/proxy/proxy_service.cc
index 6dd1b5014ec896abc49a706cb721ce1ae655918f..97b315c92eae22697eecb91b7588f406499f5d0d 100644
--- a/net/proxy/proxy_service.cc
+++ b/net/proxy/proxy_service.cc
@@ -827,6 +827,24 @@ class ProxyService::PacRequest
     config_id_ = ProxyConfig::kInvalidConfigID;
     config_source_ = PROXY_CONFIG_SOURCE_UNKNOWN;
 
+    // If the PAC script failed fatally, it needs to be reloaded. Currently,
+    // this only applies to out-of-process proxy resolution and only happens
+    // when the process crashes.
+    if (result_code == ERR_PAC_SCRIPT_TERMINATED) {
+      VLOG(1) << "Detected PAC script terminated. Resetting proxy config.";
+      // Reset the proxy config.
+      // REVIEWERS: Should the fetched proxy config be reset?
+      service_->ResetProxyConfig(false);
+
+      // If there are any pending requests, excluding this one, re-start the
+      // config fetch/apply process.
+      size_t pending_requests = service_->NumPendingRequests();
+      if (pending_requests > 1 ||
+          (pending_requests && !service_->ContainsPendingRequest(this))) {
+        service_->ApplyProxyConfigIfAvailable();
+      }
+    }
+
     return rv;
   }
 
@@ -1326,6 +1344,10 @@ void ProxyService::RemovePendingRequest(PacRequest* req) {
   pending_requests_.erase(it);
 }
 
+size_t ProxyService::NumPendingRequests() const {
+  return pending_requests_.size();
+}
+
 int ProxyService::DidFinishResolvingProxy(const GURL& url,
                                           int load_flags,
                                           NetworkDelegate* network_delegate,