Move GCP proxy code to the old [] proxy's location

1. Moved code for the GCP proxy to where the [] proxy code used to live.
3. Corrected reference to the GCP proxy location.
4. Misc changes to make ErrorProne and various tools happy.

+diekmann to LGTM terraform whitelist change.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=213630560

javatests/google/registry/proxy/metric/BackendMetricsTest.java

@@ -0,0 +1,173 @@
+// Copyright 2017 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.proxy.metric;
+
+import static com.google.monitoring.metrics.contrib.DistributionMetricSubject.assertThat;
+import static com.google.monitoring.metrics.contrib.LongMetricSubject.assertThat;
+import static google.registry.proxy.TestUtils.makeHttpPostRequest;
+import static google.registry.proxy.TestUtils.makeHttpResponse;
+
+import com.google.common.collect.ImmutableSet;
+import io.netty.handler.codec.http.FullHttpRequest;
+import io.netty.handler.codec.http.FullHttpResponse;
+import io.netty.handler.codec.http.HttpResponseStatus;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Unit tests for {@link BackendMetrics}. */
+@RunWith(JUnit4.class)
+public class BackendMetricsTest {
+
+  private final String host = "host.tld";
+  private final String certHash = "blah12345";
+  private final String protocol = "frontend protocol";
+
+  private final BackendMetrics metrics = new BackendMetrics();
+
+  @Before
+  public void setUp() {
+    metrics.resetMetric();
+  }
+
+  @Test
+  public void testSuccess_oneRequest() {
+    String content = "some content";
+    FullHttpRequest request = makeHttpPostRequest(content, host, "/");
+    metrics.requestSent(protocol, certHash, request.content().readableBytes());
+
+    assertThat(BackendMetrics.requestsCounter)
+        .hasValueForLabels(1, protocol, certHash)
+        .and()
+        .hasNoOtherValues();
+    assertThat(BackendMetrics.requestBytes)
+        .hasDataSetForLabels(ImmutableSet.of(content.length()), protocol, certHash)
+        .and()
+        .hasNoOtherValues();
+    assertThat(BackendMetrics.responsesCounter).hasNoOtherValues();
+    assertThat(BackendMetrics.responseBytes).hasNoOtherValues();
+    assertThat(BackendMetrics.latencyMs).hasNoOtherValues();
+  }
+
+  @Test
+  public void testSuccess_multipleRequests() {
+    String content1 = "some content";
+    String content2 = "some other content";
+    FullHttpRequest request1 = makeHttpPostRequest(content1, host, "/");
+    FullHttpRequest request2 = makeHttpPostRequest(content2, host, "/");
+    metrics.requestSent(protocol, certHash, request1.content().readableBytes());
+    metrics.requestSent(protocol, certHash, request2.content().readableBytes());
+
+    assertThat(BackendMetrics.requestsCounter)
+        .hasValueForLabels(2, protocol, certHash)
+        .and()
+        .hasNoOtherValues();
+    assertThat(BackendMetrics.requestBytes)
+        .hasDataSetForLabels(
+            ImmutableSet.of(content1.length(), content2.length()), protocol, certHash)
+        .and()
+        .hasNoOtherValues();
+    assertThat(BackendMetrics.responsesCounter).hasNoOtherValues();
+    assertThat(BackendMetrics.responseBytes).hasNoOtherValues();
+    assertThat(BackendMetrics.latencyMs).hasNoOtherValues();
+  }
+
+  @Test
+  public void testSuccess_oneResponse() {
+    String content = "some response";
+    FullHttpResponse response = makeHttpResponse(content, HttpResponseStatus.OK);
+    metrics.responseReceived(protocol, certHash, response, 5);
+
+    assertThat(BackendMetrics.requestsCounter).hasNoOtherValues();
+    assertThat(BackendMetrics.requestBytes).hasNoOtherValues();
+    assertThat(BackendMetrics.responsesCounter)
+        .hasValueForLabels(1, protocol, certHash, "200 OK")
+        .and()
+        .hasNoOtherValues();
+    assertThat(BackendMetrics.responseBytes)
+        .hasDataSetForLabels(ImmutableSet.of(content.length()), protocol, certHash)
+        .and()
+        .hasNoOtherValues();
+    assertThat(BackendMetrics.latencyMs)
+        .hasDataSetForLabels(ImmutableSet.of(5), protocol, certHash)
+        .and()
+        .hasNoOtherValues();
+  }
+
+  @Test
+  public void testSuccess_multipleResponses() {
+    String content1 = "some response";
+    String content2 = "other response";
+    String content3 = "a very bad response";
+    FullHttpResponse response1 = makeHttpResponse(content1, HttpResponseStatus.OK);
+    FullHttpResponse response2 = makeHttpResponse(content2, HttpResponseStatus.OK);
+    FullHttpResponse response3 = makeHttpResponse(content3, HttpResponseStatus.BAD_REQUEST);
+    metrics.responseReceived(protocol, certHash, response1, 5);
+    metrics.responseReceived(protocol, certHash, response2, 8);
+    metrics.responseReceived(protocol, certHash, response3, 2);
+
+    assertThat(BackendMetrics.requestsCounter).hasNoOtherValues();
+    assertThat(BackendMetrics.requestBytes).hasNoOtherValues();
+    assertThat(BackendMetrics.responsesCounter)
+        .hasValueForLabels(2, protocol, certHash, "200 OK")
+        .and()
+        .hasValueForLabels(1, protocol, certHash, "400 Bad Request")
+        .and()
+        .hasNoOtherValues();
+    assertThat(BackendMetrics.responseBytes)
+        .hasDataSetForLabels(
+            ImmutableSet.of(content1.length(), content2.length(), content3.length()),
+            protocol,
+            certHash)
+        .and()
+        .hasNoOtherValues();
+    assertThat(BackendMetrics.latencyMs)
+        .hasDataSetForLabels(ImmutableSet.of(5, 8, 2), protocol, certHash)
+        .and()
+        .hasNoOtherValues();
+  }
+
+  @Test
+  public void testSuccess_oneRequest_oneResponse() {
+    String requestContent = "some request";
+    String responseContent = "the only response";
+    FullHttpRequest request = makeHttpPostRequest(requestContent, host, "/");
+    FullHttpResponse response = makeHttpResponse(responseContent, HttpResponseStatus.OK);
+    metrics.requestSent(protocol, certHash, request.content().readableBytes());
+    metrics.responseReceived(protocol, certHash, response, 10);
+
+    assertThat(BackendMetrics.requestsCounter)
+        .hasValueForLabels(1, protocol, certHash)
+        .and()
+        .hasNoOtherValues();
+    assertThat(BackendMetrics.responsesCounter)
+        .hasValueForLabels(1, protocol, certHash, "200 OK")
+        .and()
+        .hasNoOtherValues();
+    assertThat(BackendMetrics.requestBytes)
+        .hasDataSetForLabels(ImmutableSet.of(requestContent.length()), protocol, certHash)
+        .and()
+        .hasNoOtherValues();
+    assertThat(BackendMetrics.responseBytes)
+        .hasDataSetForLabels(ImmutableSet.of(responseContent.length()), protocol, certHash)
+        .and()
+        .hasNoOtherValues();
+    assertThat(BackendMetrics.latencyMs)
+        .hasDataSetForLabels(ImmutableSet.of(10), protocol, certHash)
+        .and()
+        .hasNoOtherValues();
+  }
+}