Display the proxy PAC javascript errors in the NetLog....

net/proxy/proxy_service.cc

Index: net/proxy/proxy_service.cc
===================================================================
--- net/proxy/proxy_service.cc	(revision 52046)
+++ net/proxy/proxy_service.cc	(working copy)
@@ -11,6 +11,7 @@
 #include "base/message_loop.h"
 #include "base/string_util.h"
 #include "googleurl/src/gurl.h"
+#include "net/base/forwarding_net_log.h"
 #include "net/base/net_log.h"
 #include "net/base/net_errors.h"
 #include "net/base/net_util.h"
@@ -79,23 +80,29 @@
 // This factory creates V8ProxyResolvers with appropriate javascript bindings.
 class ProxyResolverFactoryForV8 : public ProxyResolverFactory {
  public:
-  // Both |async_host_resolver| and |host_resolver_loop| must remain valid for
-  // duration of our lifetime.
+  // |async_host_resolver|, |io_loop| and |net_log| must remain
+  // valid for the duration of our lifetime.
+  // Both |async_host_resolver| and |net_log| will only be operated on
+  // |io_loop|.
   ProxyResolverFactoryForV8(HostResolver* async_host_resolver,
-                            MessageLoop* host_resolver_loop)
+                            MessageLoop* io_loop,
+                            NetLog* net_log)
       : ProxyResolverFactory(true /*expects_pac_bytes*/),
         async_host_resolver_(async_host_resolver),
-        host_resolver_loop_(host_resolver_loop) {
+        io_loop_(io_loop),
+        forwarding_net_log_(
+            net_log ? new ForwardingNetLog(net_log, io_loop) : NULL) {
   }
 
   virtual ProxyResolver* CreateProxyResolver() {
     // Create a synchronous host resolver wrapper that operates
-    // |async_host_resolver_| on |host_resolver_loop_|.
+    // |async_host_resolver_| on |io_loop_|.
     SyncHostResolverBridge* sync_host_resolver =
-        new SyncHostResolverBridge(async_host_resolver_, host_resolver_loop_);
+        new SyncHostResolverBridge(async_host_resolver_, io_loop_);
 
     ProxyResolverJSBindings* js_bindings =
-        ProxyResolverJSBindings::CreateDefault(sync_host_resolver);
+        ProxyResolverJSBindings::CreateDefault(sync_host_resolver,
+                                               forwarding_net_log_.get());
 
     // ProxyResolverV8 takes ownership of |js_bindings|.
     return new ProxyResolverV8(js_bindings);
@@ -103,7 +110,11 @@
 
  private:
   scoped_refptr<HostResolver> async_host_resolver_;
-  MessageLoop* host_resolver_loop_;
+  MessageLoop* io_loop_;
+
+  // Thread-safe wrapper around a non-threadsafe NetLog implementation. This
+  // enables the proxy resolver to emit log messages from the PAC thread.
+  scoped_ptr<ForwardingNetLog> forwarding_net_log_;
 };
 
 // Creates ProxyResolvers using a non-V8 implementation.
@@ -277,7 +288,8 @@
     sync_resolver_factory =
         new ProxyResolverFactoryForV8(
             url_request_context->host_resolver(),
-            io_loop);
+            io_loop,
+            net_log);
   } else {
     sync_resolver_factory = new ProxyResolverFactoryForNonV8();
   }