Extract NativeLibraryTestRule logic to static util class

NativeLibraryTestRule doesn't use any TestRule behavior, so refactor it
to a static util class so that it can be more easily referenced by other
TestRules.

Original class kept as a wrapper class until all usages (including
downstream) are removed in follow-up CLs.

Bug: 1096666
Change-Id: Ieacec3cc04b34be321b6eaa65f6c9a524b7f71c7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2251099
Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
Commit-Queue: Natalie Chouinard <chouinard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#780341}

content/public/test/android/BUILD.gn

@@ -30,6 +30,7 @@ android_library("content_java_test_support") {
     "javatests/src/org/chromium/content_public/browser/test/ChildProcessAllocatorSettingsHook.java",
     "javatests/src/org/chromium/content_public/browser/test/ContentJUnit4ClassRunner.java",
     "javatests/src/org/chromium/content_public/browser/test/NativeLibraryTestRule.java",
+    "javatests/src/org/chromium/content_public/browser/test/NativeLibraryTestUtils.java",
     "javatests/src/org/chromium/content_public/browser/test/RenderFrameHostTestExt.java",
     "javatests/src/org/chromium/content_public/browser/test/mock/MockNavigationController.java",
     "javatests/src/org/chromium/content_public/browser/test/mock/MockRenderFrameHost.java",

content/public/test/android/javatests/src/org/chromium/content_public/browser/test/NativeLibraryTestRule.java

@@ -4,29 +4,25 @@
 
 package org.chromium.content_public.browser.test;
 
-import org.junit.Assert;
 import org.junit.rules.TestRule;
 import org.junit.runner.Description;
 import org.junit.runners.model.Statement;
 
-import org.chromium.base.ThreadUtils;
-import org.chromium.base.library_loader.LibraryLoader;
-import org.chromium.base.library_loader.LibraryProcessType;
-import org.chromium.content_public.browser.BrowserStartupController;
-import org.chromium.content_public.browser.UiThreadTaskTraits;
-import org.chromium.ui.resources.ResourceExtractor;
-
 /**
  * TestRule that adds support for loading and dealing with native libraries.
  *
  * NativeLibraryTestRule does not interact with any Activity.
+ *
+ * TODO(crbug.com/1096666): Remove this class in favor of using {@link NativeLibraryTestUtils}
+ * directly.
  */
+@Deprecated
 public class NativeLibraryTestRule implements TestRule {
     /**
      * Loads the native library on the activity UI thread (must not be called from the UI thread).
      */
     public void loadNativeLibraryNoBrowserProcess() {
-        handleNativeInitialization(false);
+        NativeLibraryTestUtils.loadNativeLibraryNoBrowserProcess();
     }
 
     /**
@@ -34,32 +30,7 @@ public class NativeLibraryTestRule implements TestRule {
      * After loading the library, this will initialize the browser process.
      */
     public void loadNativeLibraryAndInitBrowserProcess() {
-        handleNativeInitialization(true);
-    }
-
-    private void handleNativeInitialization(final boolean initBrowserProcess) {
-        Assert.assertFalse(ThreadUtils.runningOnUiThread());
-
-        // LibraryLoader is not in general multithreaded; as other InstrumentationTestCase code
-        // (specifically, ChromeBrowserProvider) uses it from the main thread we must do
-        // likewise.
-        ThreadUtils.runOnUiThreadBlocking(() -> { nativeInitialization(initBrowserProcess); });
-    }
-
-    private void nativeInitialization(boolean initBrowserProcess) {
-        LibraryLoader.getInstance().setLibraryProcessType(LibraryProcessType.PROCESS_BROWSER);
-        if (initBrowserProcess) {
-            // Extract compressed resource paks.
-            ResourceExtractor resourceExtractor = ResourceExtractor.get();
-            resourceExtractor.setResultTraits(UiThreadTaskTraits.BOOTSTRAP);
-            resourceExtractor.startExtractingResources("en");
-            resourceExtractor.waitForCompletion();
-
-            BrowserStartupController.getInstance().startBrowserProcessesSync(
-                    LibraryProcessType.PROCESS_BROWSER, false);
-        } else {
-            LibraryLoader.getInstance().ensureInitialized();
-        }
+        NativeLibraryTestUtils.loadNativeLibraryAndInitBrowserProcess();
     }
 
     @Override

content/public/test/android/javatests/src/org/chromium/content_public/browser/test/NativeLibraryTestUtils.java

@@ -0,0 +1,59 @@
+// Copyright 2020 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.content_public.browser.test;
+
+import org.junit.Assert;
+
+import org.chromium.base.ThreadUtils;
+import org.chromium.base.library_loader.LibraryLoader;
+import org.chromium.base.library_loader.LibraryProcessType;
+import org.chromium.content_public.browser.BrowserStartupController;
+import org.chromium.content_public.browser.UiThreadTaskTraits;
+import org.chromium.ui.resources.ResourceExtractor;
+
+/**
+ * Provides test support for loading and dealing with native libraries.
+ */
+public class NativeLibraryTestUtils {
+    /**
+     * Loads the native library on the activity UI thread (must not be called from the UI thread).
+     */
+    public static void loadNativeLibraryNoBrowserProcess() {
+        handleNativeInitialization(false);
+    }
+
+    /**
+     * Loads the native library on the activity UI thread (must not be called from the UI thread).
+     * After loading the library, this will initialize the browser process.
+     */
+    public static void loadNativeLibraryAndInitBrowserProcess() {
+        handleNativeInitialization(true);
+    }
+
+    private static void handleNativeInitialization(final boolean initBrowserProcess) {
+        Assert.assertFalse(ThreadUtils.runningOnUiThread());
+
+        // LibraryLoader is not in general multithreaded; as other InstrumentationTestCase code
+        // (specifically, ChromeBrowserProvider) uses it from the main thread we must do
+        // likewise.
+        ThreadUtils.runOnUiThreadBlocking(() -> { nativeInitialization(initBrowserProcess); });
+    }
+
+    private static void nativeInitialization(boolean initBrowserProcess) {
+        LibraryLoader.getInstance().setLibraryProcessType(LibraryProcessType.PROCESS_BROWSER);
+        if (initBrowserProcess) {
+            // Extract compressed resource paks.
+            ResourceExtractor resourceExtractor = ResourceExtractor.get();
+            resourceExtractor.setResultTraits(UiThreadTaskTraits.BOOTSTRAP);
+            resourceExtractor.startExtractingResources("en");
+            resourceExtractor.waitForCompletion();
+
+            BrowserStartupController.getInstance().startBrowserProcessesSync(
+                    LibraryProcessType.PROCESS_BROWSER, false);
+        } else {
+            LibraryLoader.getInstance().ensureInitialized();
+        }
+    }
+}