Replace robolectric RuntimeEnvironment with androidx ApplicationProvider

Documentation of RuntimeEnvironment#application says:
  Deprecated. Please migrate to
  androidx.test.core.app.ApplicationProvider#getApplicationContext

Change-Id: I5f5b71e29edf99f4b6ee692247ea6910a0eb692c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2305369Reviewed-by: Gang Wu <gangwu@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Auto-Submit: who/bttk <bttk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#789951}

base/BUILD.gn

@@ -3788,6 +3788,7 @@ if (is_android) {
     deps = [
       ":base_java",
       "//testing/android/junit:junit_test_support",
+      "//third_party/android_deps:androidx_test_core_java",
       "//third_party/android_deps:androidx_test_monitor_java",
       "//third_party/android_deps:androidx_test_uiautomator_uiautomator_java",
       "//third_party/android_deps:robolectric_all_java",

base/test/android/junit/src/org/chromium/base/test/BaseRobolectricTestRunner.java

@@ -4,9 +4,10 @@
 
 package org.chromium.base.test;
 
+import androidx.test.core.app.ApplicationProvider;
+
 import org.junit.runners.model.InitializationError;
 import org.robolectric.DefaultTestLifecycle;
-import org.robolectric.RuntimeEnvironment;
 import org.robolectric.TestLifecycle;
 
 import org.chromium.base.ApplicationStatus;
@@ -28,8 +29,9 @@ public class BaseRobolectricTestRunner extends LocalRobolectricTestRunner {
     public static class BaseTestLifecycle extends DefaultTestLifecycle {
         @Override
         public void beforeTest(Method method) {
-            ContextUtils.initApplicationContextForTests(RuntimeEnvironment.application);
-            ApplicationStatus.initialize(RuntimeEnvironment.application);
+            ContextUtils.initApplicationContextForTests(
+                    ApplicationProvider.getApplicationContext());
+            ApplicationStatus.initialize(ApplicationProvider.getApplicationContext());
             CommandLine.init(null);
             super.beforeTest(method);
         }

base/test/android/junit/src/org/chromium/base/test/util/TestRunnerTestRule.java

@@ -12,6 +12,8 @@ import android.content.Context;
 import android.os.Bundle;
 import android.support.test.InstrumentationRegistry;
 
+import androidx.test.core.app.ApplicationProvider;
+
 import org.junit.Assert;
 import org.junit.rules.ExternalResource;
 import org.junit.runner.Description;
@@ -21,7 +23,6 @@ import org.junit.runner.notification.RunListener;
 import org.junit.runner.notification.RunNotifier;
 import org.junit.runners.BlockJUnit4ClassRunner;
 import org.junit.runners.model.InitializationError;
-import org.robolectric.RuntimeEnvironment;
 
 import java.lang.reflect.InvocationTargetException;
 import java.util.ArrayList;
@@ -49,7 +50,7 @@ class TestRunnerTestRule extends ExternalResource {
         Instrumentation instrumentation = new Instrumentation() {
             @Override
             public Context getTargetContext() {
-                return RuntimeEnvironment.application;
+                return ApplicationProvider.getApplicationContext();
             }
         };
         InstrumentationRegistry.registerInstance(instrumentation, new Bundle());