[Android] Add a histogram to record number of android accounts on device

Adds a histogram that records number of android accounts present on
device even if the user isn't signed in.

Bug: 1025410
Change-Id: Ide66597ea3da5857e6f7ccd5bec018b54ebc03e6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2607306Reviewed-by: Alex Ilin <alexilin@chromium.org>
Reviewed-by: Boris Sazonov <bsazonov@chromium.org>
Reviewed-by: Alice Wang <aliceywang@chromium.org>
Commit-Queue: Tanmoy Mollik <triploblastic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840676}

components/signin/core/browser/android/java/src/org/chromium/components/signin/AccountManagerFacadeImpl.java

@@ -448,6 +448,10 @@ public class AccountManagerFacadeImpl implements AccountManagerFacade {
 
         @Override
         protected void onPostExecute(Void v) {
+            // Records number of Android accounts present on device.
+            RecordHistogram.recordExactLinearHistogram(
+                    "Signin.AndroidNumberOfDeviceAccounts", tryGetGoogleAccounts().size(), 50);
+
             for (Runnable callback : mCallbacksWaitingForCachePopulation) {
                 callback.run();
             }

components/signin/core/browser/android/junit/src/org/chromium/components/signin/test/AccountManagerFacadeRobolectricTest.java

@@ -7,6 +7,7 @@ package org.chromium.components.signin.test;
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.spy;
 import static org.mockito.Mockito.verify;
+import static org.mockito.MockitoAnnotations.initMocks;
 import static org.robolectric.Shadows.shadowOf;
 
 import android.accounts.Account;
@@ -23,11 +24,15 @@ import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.mockito.Mock;
 import org.robolectric.RuntimeEnvironment;
 import org.robolectric.annotation.Config;
 
+import org.chromium.base.metrics.UmaRecorder;
+import org.chromium.base.metrics.UmaRecorderHolder;
 import org.chromium.base.task.test.CustomShadowAsyncTask;
 import org.chromium.base.test.BaseRobolectricTestRunner;
+import org.chromium.base.test.util.CallbackHelper;
 import org.chromium.components.signin.AccountManagerDelegateException;
 import org.chromium.components.signin.AccountManagerFacade;
 import org.chromium.components.signin.AccountManagerFacadeImpl;
@@ -39,6 +44,7 @@ import org.chromium.components.signin.test.util.FakeAccountManagerDelegate;
 import org.chromium.testing.local.CustomShadowUserManager;
 
 import java.util.List;
+import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.AtomicInteger;
 
 /**
@@ -52,8 +58,13 @@ public class AccountManagerFacadeRobolectricTest {
     private FakeAccountManagerDelegate mDelegate;
     private AccountManagerFacade mFacade;
 
+    @Mock
+    private UmaRecorder mUmaRecorderMock;
+
     @Before
     public void setUp() {
+        initMocks(this);
+        UmaRecorderHolder.setNonNativeDelegate(mUmaRecorderMock);
         Context context = RuntimeEnvironment.application;
         UserManager userManager = (UserManager) context.getSystemService(Context.USER_SERVICE);
         mShadowUserManager = (CustomShadowUserManager) shadowOf(userManager);
@@ -87,6 +98,22 @@ public class AccountManagerFacadeRobolectricTest {
         verify(delegate).registerObservers();
     }
 
+    @Test
+    @SmallTest
+    public void testCountOfAccountLoggedAfterAccountsFetched() {
+        addTestAccount("test@gmail.com");
+        AccountManagerFacade facade = new AccountManagerFacadeImpl(mDelegate);
+        CallbackHelper callbackHelper = new CallbackHelper();
+        facade.runAfterCacheIsPopulated(() -> callbackHelper.notifyCalled());
+        try {
+            callbackHelper.waitForFirst();
+        } catch (TimeoutException e) {
+            throw new RuntimeException("Timed out waiting for callback", e);
+        }
+        verify(mUmaRecorderMock)
+                .recordLinearHistogram("Signin.AndroidNumberOfDeviceAccounts", 1, 1, 50, 51);
+    }
+
     @Test
     @SmallTest
     public void testCanonicalAccount() {

tools/metrics/histograms/histograms_xml/signin/histograms.xml

@@ -173,6 +173,15 @@ prefs when the profile is loaded.  -->
   </summary>
 </histogram>
 
+<histogram name="Signin.AndroidNumberOfDeviceAccounts" units="accounts"
+    expires_after="2021-08-31">
+  <owner>triploblastic@chromium.org</owner>
+  <owner>aliceywang@chromium.org</owner>
+  <summary>
+    The number of Android accounts present on the device. Recorded on startup.
+  </summary>
+</histogram>
+
 <histogram name="Signin.AndroidPopulateAccountCacheWaitingTime" units="ms"
     expires_after="2021-08-16">
   <owner>bsazonov@chromium.org</owner>