Make the v8 Isolate used in the proxy resolver explicit.

net/base/run_all_unittests.cc

Index: net/base/run_all_unittests.cc
diff --git a/net/base/run_all_unittests.cc b/net/base/run_all_unittests.cc
index 57a18b815a82b615a7e3a5c83b14a52011cf9e02..f0e817692cb9f86031cff86140b954094ec04671 100644
--- a/net/base/run_all_unittests.cc
+++ b/net/base/run_all_unittests.cc
@@ -16,6 +16,10 @@
 #include "net/android/net_jni_registrar.h"
 #endif
 
+#if !defined(OS_IOS)
+#include "net/proxy/proxy_resolver_v8.h"
+#endif
+
 using net::internal::ClientSocketPoolBaseHelper;
 using net::SpdySession;
 
@@ -43,5 +47,10 @@ int main(int argc, char** argv) {
   // single-threaded.
   net::EnableSSLServerSockets();
 
+#if !defined(OS_IOS)
+  // This has to be done on the main thread.
+  net::ProxyResolverV8::RememberDefaultIsolate();
+#endif
+
   return test_suite.Run();
 }