Re-adds the UkmTest.java file and re-adds two tests.

This partially reverts crrev.com/c/2247706 and crrev.com/c/2245049.

A couple of the Android tests that were ported to
chrome/browser/metrics/ukm_browsertest.cc are flaky. Temporarily
re-adding this test file ensures we have coverage while we fix the
tests. The tests being re-added are consentAddedButNoSyncCheck and
singleSyncSignoutCheck.

Also, note that mSyncTestRule.startMainActivityOnBlankPage(); is being
removed from setUp() because this is done before setUp() here [1].
Calling startMainActivityOnBlankPage() twice, once via SyncTestRule and
again via setUp(), results in a TimeoutException [2] the second time
startMainActivityOnBlankPage() is called. A log is in [3].

[1] https://source.chromium.org/chromium/chromium/src/+/master:chrome/android/javatests/src/org/chromium/chrome/browser/sync/SyncTestRule.java;l=358
[2] java.lang.RuntimeException: java.util.concurrent.TimeoutException: No Activity reached target state.
[3] https://paste.googleplex.com/6459114528964608

Original change's description:
> Remove a UKM test that should have been deleted.
>
> In the below comment, it was requested that the corresponding Android
> test be removed.
> https://chromium-review.googlesource.com/c/chromium/src/+/1869007/12/chrome/browser/metrics/ukm_browsertest.cc#b646
>
> Bug: 1049736
> Change-Id: Iac3ff27fc4d8145bef53d45aecb54efeda5e55f6
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2245049
> Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
> Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
> Reviewed-by: Marc Treib <treib@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#779285}

TBR=rkaplow@chromium.org,treib@chromium.org,caitlinfischer@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1049736
Change-Id: I7dbc36f70ec7b9a567c7c0bb1594081c5e08dadd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2578057Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Reviewed-by: Caitlin Fischer <caitlinfischer@google.com>
Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
Cr-Commit-Position: refs/heads/master@{#835201}

chrome/android/chrome_test_java_sources.gni

@@ -545,6 +545,7 @@ chrome_test_java_sources = [
   "javatests/src/org/chromium/chrome/browser/sync/SyncTest.java",
   "javatests/src/org/chromium/chrome/browser/sync/SyncTestRule.java",
   "javatests/src/org/chromium/chrome/browser/sync/TypedUrlsTest.java",
+  "javatests/src/org/chromium/chrome/browser/sync/UkmTest.java",
   "javatests/src/org/chromium/chrome/browser/sync/ui/PassphraseActivityTest.java",
   "javatests/src/org/chromium/chrome/browser/sync/ui/PassphraseTypeDialogFragmentTest.java",
   "javatests/src/org/chromium/chrome/browser/tab/InterceptNavigationDelegateTest.java",

chrome/android/javatests/src/org/chromium/chrome/browser/sync/UkmTest.java

+// Copyright 2018 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.sync;
+
+import androidx.test.filters.SmallTest;
+
+import org.junit.After;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.chromium.base.test.util.CommandLineFlags;
+import org.chromium.chrome.browser.flags.ChromeSwitches;
+import org.chromium.chrome.browser.metrics.UmaSessionStats;
+import org.chromium.chrome.browser.tab.Tab;
+import org.chromium.chrome.test.ChromeJUnit4ClassRunner;
+import org.chromium.components.signin.base.CoreAccountInfo;
+import org.chromium.content_public.browser.test.util.JavaScriptUtils;
+import org.chromium.content_public.browser.test.util.TestThreadUtils;
+import org.chromium.ui.base.PageTransition;
+
+/**
+ * Tests for UKM Sync integration.
+ */
+@RunWith(ChromeJUnit4ClassRunner.class)
+@CommandLineFlags.Add({ChromeSwitches.DISABLE_FIRST_RUN_EXPERIENCE})
+// Note we do not use the 'force-enable-metrics-reporting' flag for these tests as they would
+// ignore the Sync setting we are verifying.
+
+public class UkmTest {
+    @Rule
+    public SyncTestRule mSyncTestRule = new SyncTestRule();
+
+    private static final String DEBUG_PAGE = "chrome://ukm/";
+
+    @Before
+    public void setUp() {
+        TestThreadUtils.runOnUiThreadBlocking(
+                () -> UmaSessionStats.initMetricsAndCrashReportingForTesting());
+    }
+
+    @After
+    public void tearDown() {
+        TestThreadUtils.runOnUiThreadBlocking(
+                () -> UmaSessionStats.unSetMetricsAndCrashReportingForTesting());
+    }
+
+    public String getElementContent(Tab normalTab, String elementId) throws Exception {
+        mSyncTestRule.loadUrlInTab(
+                DEBUG_PAGE, PageTransition.TYPED | PageTransition.FROM_ADDRESS_BAR, normalTab);
+        return JavaScriptUtils.executeJavaScriptAndWaitForResult(normalTab.getWebContents(),
+                "document.getElementById('" + elementId + "').textContent");
+    }
+
+    public boolean isUkmEnabled(Tab normalTab) throws Exception {
+        String state = getElementContent(normalTab, "state");
+        Assert.assertTrue(
+                "UKM state: " + state, state.equals("\"ENABLED\"") || state.equals("\"DISABLED\""));
+        return state.equals("\"ENABLED\"");
+    }
+
+    public String getUkmClientId(Tab normalTab) throws Exception {
+        return getElementContent(normalTab, "clientid");
+    }
+
+    @Test
+    @SmallTest
+    // TODO(crbug/1049736): Enable the corrersponding C++ test and delete this
+    // test.
+    public void consentAddedButNoSyncCheck() throws Exception {
+        // Keep in sync with UkmBrowserTest.ConsentAddedButNoSyncCheck in
+        // chrome/browser/metrics/ukm_browsertest.cc.
+        // Make sure that providing consent doesn't enable UKM when sync is disabled.
+
+        TestThreadUtils.runOnUiThreadBlocking(
+                () -> UmaSessionStats.updateMetricsAndCrashReportingForTesting(false));
+        Tab normalTab = mSyncTestRule.getActivity().getActivityTab();
+        Assert.assertFalse("UKM Enabled:", isUkmEnabled(normalTab));
+
+        // Enable consent, Sync still not enabled so UKM should be disabled.
+        TestThreadUtils.runOnUiThreadBlocking(
+                () -> UmaSessionStats.updateMetricsAndCrashReportingForTesting(true));
+        Assert.assertFalse("UKM Enabled:", isUkmEnabled(normalTab));
+
+        // Finally, sign in and UKM is enabled.
+        CoreAccountInfo account = mSyncTestRule.setUpAccountAndSignInForTesting();
+        Assert.assertTrue("UKM Enabled:", isUkmEnabled(normalTab));
+    }
+
+    @Test
+    @SmallTest
+    // TODO(crbug/1049736): Enable the corrersponding C++ test and delete this
+    // test.
+    public void singleSyncSignoutCheck() throws Exception {
+        // Keep in sync with UkmBrowserTest.SingleSyncSignoutCheck in
+        // chrome/browser/metrics/ukm_browsertest.cc.
+        // Make sure that UKM is disabled when an secondary passphrase is set.
+
+        TestThreadUtils.runOnUiThreadBlocking(
+                () -> UmaSessionStats.updateMetricsAndCrashReportingForTesting(true));
+
+        // Enable a Syncing account.
+        CoreAccountInfo account = mSyncTestRule.setUpAccountAndSignInForTesting();
+        Tab normalTab = mSyncTestRule.getActivity().getActivityTab();
+        Assert.assertTrue("UKM Enabled:", isUkmEnabled(normalTab));
+
+        String clientId = getUkmClientId(normalTab);
+
+        // Signing out should disable UKM.
+        mSyncTestRule.signOut();
+
+        Assert.assertFalse("UKM Enabled:", isUkmEnabled(normalTab));
+
+        // Client ID should have been reset.
+        Assert.assertNotEquals("Client id:", clientId, getUkmClientId(normalTab));
+    }
+}