Remove redundant mapping of net errors to strings.

components/cronet/android/org_chromium_net_UrlRequest.cc

Index: components/cronet/android/org_chromium_net_UrlRequest.cc
diff --git a/components/cronet/android/org_chromium_net_UrlRequest.cc b/components/cronet/android/org_chromium_net_UrlRequest.cc
index f96f16422db26e8149403dbd33731ec82b97c459..3d633261f9e973c3cc63eaeb47c4409fc7dfee1a 100644
--- a/components/cronet/android/org_chromium_net_UrlRequest.cc
+++ b/components/cronet/android/org_chromium_net_UrlRequest.cc
@@ -251,10 +251,11 @@ static jstring GetErrorString(JNIEnv* env,
   URLRequestPeer* request = reinterpret_cast<URLRequestPeer*>(urlRequestPeer);
   int error_code = request->error_code();
   char buffer[200];
+  std::string error_string = net::ErrorToString(error_code);
   snprintf(buffer,
            sizeof(buffer),
            "System error: %s(%d)",
-           net::ErrorToString(error_code),
+           error_string.c_str(),
            error_code);
   return ConvertUTF8ToJavaString(env, buffer).Release();
 }