Re-add Stackdriver metrics code

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=146000275

javatests/google/registry/monitoring/metrics/stackdriver/GoogleJsonResponseExceptionHelper.java

@@ -0,0 +1,171 @@
+// Copyright 2016 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.monitoring.metrics.stackdriver;
+
+import com.google.api.client.googleapis.json.GoogleJsonResponseException;
+import com.google.api.client.http.GenericUrl;
+import com.google.api.client.http.HttpContent;
+import com.google.api.client.http.HttpRequest;
+import com.google.api.client.http.HttpRequestFactory;
+import com.google.api.client.http.HttpResponse;
+import com.google.api.client.http.HttpTransport;
+import com.google.api.client.http.LowLevelHttpRequest;
+import com.google.api.client.http.LowLevelHttpResponse;
+import com.google.api.client.json.jackson2.JacksonFactory;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+/** A helper to create instances of {@link GoogleJsonResponseException}. */
+public class GoogleJsonResponseExceptionHelper {
+  /**
+   * @param statusCode the status code that should be in the returned {@link
+   *     GoogleJsonResponseException}
+   * @return a {@link GoogleJsonResponseException} with the status code {@code statusCode}
+   * @throws IOException shouldn't occur
+   */
+  public static GoogleJsonResponseException create(int statusCode) throws IOException {
+    HttpResponse response = createHttpResponse(statusCode, null);
+    return GoogleJsonResponseException.from(new JacksonFactory(), response);
+  }
+
+  public static HttpResponse createHttpResponse(int statusCode, InputStream content)
+      throws IOException {
+    FakeHttpTransport transport = new FakeHttpTransport(statusCode, content);
+    HttpRequestFactory factory = transport.createRequestFactory();
+    HttpRequest request =
+        factory.buildRequest(
+            "foo", new GenericUrl("http://example.com/bar"), new EmptyHttpContent());
+    request.setThrowExceptionOnExecuteError(false);
+    return request.execute();
+  }
+
+  private static class FakeHttpTransport extends HttpTransport {
+    private final int statusCode;
+    private final InputStream content;
+
+    FakeHttpTransport(int statusCode, InputStream content) {
+      this.statusCode = statusCode;
+      this.content = content;
+    }
+
+    @Override
+    protected LowLevelHttpRequest buildRequest(String method, String url) throws IOException {
+      return new FakeLowLevelHttpRequest(statusCode, content);
+    }
+  }
+
+  private static class FakeLowLevelHttpRequest extends LowLevelHttpRequest {
+    private final int statusCode;
+    private final InputStream content;
+
+    FakeLowLevelHttpRequest(int statusCode, InputStream content) {
+      this.statusCode = statusCode;
+      this.content = content;
+    }
+
+    @Override
+    public void addHeader(String name, String value) throws IOException {
+      // Nothing!
+    }
+
+    @Override
+    public LowLevelHttpResponse execute() throws IOException {
+      return new FakeLowLevelHttpResponse(statusCode, content);
+    }
+  }
+
+  private static class FakeLowLevelHttpResponse extends LowLevelHttpResponse {
+    private final int statusCode;
+    private final InputStream content;
+
+    FakeLowLevelHttpResponse(int statusCode, InputStream content) {
+      this.statusCode = statusCode;
+      this.content = content;
+    }
+
+    @Override
+    public InputStream getContent() throws IOException {
+      return content;
+    }
+
+    @Override
+    public String getContentEncoding() throws IOException {
+      return null;
+    }
+
+    @Override
+    public long getContentLength() throws IOException {
+      return 0;
+    }
+
+    @Override
+    public String getContentType() throws IOException {
+      return "text/json";
+    }
+
+    @Override
+    public String getStatusLine() throws IOException {
+      return null;
+    }
+
+    @Override
+    public int getStatusCode() throws IOException {
+      return statusCode;
+    }
+
+    @Override
+    public String getReasonPhrase() throws IOException {
+      return null;
+    }
+
+    @Override
+    public int getHeaderCount() throws IOException {
+      return 0;
+    }
+
+    @Override
+    public String getHeaderName(int index) throws IOException {
+      return null;
+    }
+
+    @Override
+    public String getHeaderValue(int index) throws IOException {
+      return null;
+    }
+  }
+
+  private static class EmptyHttpContent implements HttpContent {
+    @Override
+    public long getLength() throws IOException {
+      return 0;
+    }
+
+    @Override
+    public String getType() {
+      return "text/json";
+    }
+
+    @Override
+    public boolean retrySupported() {
+      return false;
+    }
+
+    @Override
+    public void writeTo(OutputStream out) throws IOException {
+      // Nothing!
+    }
+  }
+}