Mock out native call to log memory usage in NativeBackgroundTaskTest.

This call happens rarely (1/60000), but it causes a crash when it does.

Change-Id: I0d584f0cd4017252ab80fc23fe0a41124bd13c73
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1880705Reviewed-by: Mohamed Heikal <mheikal@chromium.org>
Reviewed-by: David Trainor <dtrainor@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710444}

chrome/android/java/src/org/chromium/chrome/browser/metrics/BackgroundTaskMemoryMetricsEmitter.java

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.metrics;
+import org.chromium.base.VisibleForTesting;
 import org.chromium.base.annotations.NativeMethods;
 
 /**
@@ -22,8 +23,9 @@ public class BackgroundTaskMemoryMetricsEmitter {
         BackgroundTaskMemoryMetricsEmitterJni.get().reportMemoryUsage(isReducedMode, taskTypeAffix);
     }
 
+    @VisibleForTesting
     @NativeMethods
-    interface Natives {
+    public interface Natives {
         void reportMemoryUsage(boolean isReducedMode, String taskTypeAffix);
     }
 }

chrome/android/junit/src/org/chromium/chrome/browser/background_task_scheduler/NativeBackgroundTaskTest.java

@@ -18,6 +18,7 @@ import static org.mockito.Mockito.verify;
 import android.content.Context;
 
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.ArgumentCaptor;
@@ -33,8 +34,11 @@ import org.chromium.base.library_loader.LoaderErrors;
 import org.chromium.base.library_loader.ProcessInitException;
 import org.chromium.base.test.BaseRobolectricTestRunner;
 import org.chromium.base.test.util.Feature;
+import org.chromium.base.test.util.JniMocker;
 import org.chromium.chrome.browser.init.BrowserParts;
 import org.chromium.chrome.browser.init.ChromeBrowserInitializer;
+import org.chromium.chrome.browser.metrics.BackgroundTaskMemoryMetricsEmitter;
+import org.chromium.chrome.browser.metrics.BackgroundTaskMemoryMetricsEmitterJni;
 import org.chromium.components.background_task_scheduler.BackgroundTask;
 import org.chromium.components.background_task_scheduler.TaskIds;
 import org.chromium.components.background_task_scheduler.TaskParameters;
@@ -43,7 +47,7 @@ import org.chromium.content_public.browser.BrowserStartupController;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 
-/** Unit tests for {@link BackgroundTaskScheduler}. */
+/** Unit tests for {@link NativeBackgroundTask}. */
 @RunWith(BaseRobolectricTestRunner.class)
 @Config(manifest = Config.NONE)
 public class NativeBackgroundTaskTest {
@@ -112,8 +116,12 @@ public class NativeBackgroundTaskTest {
     private TaskFinishedCallback mCallback;
     private TestNativeBackgroundTask mTask;
 
+    @Rule
+    public final JniMocker mocker = new JniMocker();
     @Mock
     private ChromeBrowserInitializer mChromeBrowserInitializer;
+    @Mock
+    BackgroundTaskMemoryMetricsEmitter.Natives mEmitterNativeMock;
     @Captor
     ArgumentCaptor<BrowserParts> mBrowserParts;
 
@@ -228,6 +236,7 @@ public class NativeBackgroundTaskTest {
     @Before
     public void setUp() {
         MockitoAnnotations.initMocks(this);
+        mocker.mock(BackgroundTaskMemoryMetricsEmitterJni.TEST_HOOKS, mEmitterNativeMock);
         mBrowserStartupController = new TestBrowserStartupController();
         mCallback = new TaskFinishedCallback();
         mTask = new TestNativeBackgroundTask(mBrowserStartupController);