Remove URLRequestJob::GetResponseCode implementations from some tests.

chrome/browser/predictors/resource_prefetch_predictor_unittest.cc

Index: chrome/browser/predictors/resource_prefetch_predictor_unittest.cc
diff --git a/chrome/browser/predictors/resource_prefetch_predictor_unittest.cc b/chrome/browser/predictors/resource_prefetch_predictor_unittest.cc
index b21c918b8eb356b135f376a00e4f3762e6ac0379..5815d41a3620b4af8c64f67c3417b5d295f5b7bd 100644
--- a/chrome/browser/predictors/resource_prefetch_predictor_unittest.cc
+++ b/chrome/browser/predictors/resource_prefetch_predictor_unittest.cc
@@ -70,7 +70,6 @@ class MockURLRequestJob : public net::URLRequestJob {
 
  protected:
   void Start() override { NotifyHeadersComplete(); }
-  int GetResponseCode() const override { return 200; }
   void GetResponseInfo(net::HttpResponseInfo* info) override {
     *info = response_info_;
   }