Add UMA for CopylessPaste cache

chrome/android/junit/src/org/chromium/chrome/browser/AppIndexingUtilTest.java

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser;
 
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.doAnswer;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.eq;
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
 
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 import org.mockito.Spy;
 import org.mockito.invocation.InvocationOnMock;
 import org.mockito.stubbing.Answer;
 import org.robolectric.annotation.Config;
 
 import org.chromium.blink.mojom.document_metadata.CopylessPaste;
 import org.chromium.blink.mojom.document_metadata.WebPage;
 import org.chromium.chrome.browser.historyreport.AppIndexingReporter;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.testing.local.LocalRobolectricTestRunner;
 import org.chromium.url.mojom.Url;
 
 /**
  * Unit tests for {@link org.chromium.chrome.browser.AppIndexingUtil}.
  */
 @RunWith(LocalRobolectricTestRunner.class)
 @Config(manifest = Config.NONE)
 public class AppIndexingUtilTest {
+    @Rule
+    public DisableHistogramsRule mDisableHistogramsRule = new DisableHistogramsRule();
     @Spy
     AppIndexingUtil mUtil = new AppIndexingUtil();
     @Mock
     private AppIndexingReporter mReporter;
     @Mock
     private CopylessPasteTestImpl mCopylessPaste;
     @Mock
     private Tab mTab;
 
     @Before
@@ skipping 73 matching lines @@
     }
 
     private Url createUrl(String s) {
         Url url = new Url();
         url.url = s;
         return url;
     }
 
     abstract static class CopylessPasteTestImpl implements CopylessPaste {}
 }