Add TestRules for content shell test and refactor test bases

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

Index: content/public/test/android/javatests/src/org/chromium/content/browser/test/NativeLibraryTestRule.java
diff --git a/content/public/test/android/javatests/src/org/chromium/content/browser/test/NativeLibraryTestRule.java b/content/public/test/android/javatests/src/org/chromium/content/browser/test/NativeLibraryTestRule.java
new file mode 100644
index 0000000000000000000000000000000000000000..a673f124a5c402addb3e5fd96c5fd6b019bb5945
--- /dev/null
+++ b/content/public/test/android/javatests/src/org/chromium/content/browser/test/NativeLibraryTestRule.java
@@ -0,0 +1,40 @@
+// Copyright 2017 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.browser.test;
+
+import android.support.test.InstrumentationRegistry;
+
+import org.junit.rules.TestRule;
+import org.junit.runner.Description;
+import org.junit.runners.model.Statement;
+
+/**
+ * TestRule that adds support for loading and dealing with native libraries.
+ *
+ * NativeLibraryTestRule does not interact with any Activity.
+ */
+public class NativeLibraryTestRule implements TestRule {
+    private final NativeLibraryTestCommon mTestCommon = new NativeLibraryTestCommon();
+
+    /**
+     * Loads the native library on the activity UI thread (must not be called from the UI thread).
+     */
+    public void loadNativeLibraryNoBrowserProcess() {
+        mTestCommon.handleNativeInitialization(false, InstrumentationRegistry.getInstrumentation());
+    }
+
+    /**
+     * 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 void loadNativeLibraryAndInitBrowserProcess() {
+        mTestCommon.handleNativeInitialization(true, InstrumentationRegistry.getInstrumentation());
+    }
+
+    @Override
+    public Statement apply(Statement base, Description description) {
+        return base;
+    }
+}