Add Cronet Test App that uses libcronet_tests.so with net test utilities.

components/cronet/android/test/cronet_tests_jni.cc

Index: components/cronet/android/test/cronet_tests_jni.cc
diff --git a/components/cronet/android/test/cronet_tests_jni.cc b/components/cronet/android/test/cronet_tests_jni.cc
new file mode 100644
index 0000000000000000000000000000000000000000..354ef9ab85e49e8a28bc29f12991e2f58ee32cd4
--- /dev/null
+++ b/components/cronet/android/test/cronet_tests_jni.cc
@@ -0,0 +1,44 @@
+// Copyright 2014 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.
+
+#include <jni.h>
+
+#include "base/android/base_jni_registrar.h"
+#include "base/android/jni_android.h"
+#include "base/android/jni_registrar.h"
+#include "components/cronet/android/cronet_loader.h"
+
+namespace {
+
+const base::android::RegistrationMethod kCronetTestsRegisteredMethods[] = {
+  {"BaseAndroid", base::android::RegisterJni},
+};
+
+}  // namespace
+
+// This is called by the VM when the shared library is first loaded.
+// Checks the available version of JNI. Also, caches Java reflection artifacts.
+extern "C" jint JNI_OnLoad(JavaVM* vm, void* reserved) {
+  JNIEnv* env;
+  if (vm->GetEnv(reinterpret_cast<void**>(&env), JNI_VERSION_1_6) != JNI_OK) {
+    return -1;
+  }
+
+  jint cronet_onload = cronet::CronetOnLoad(vm, reserved);
+  if (cronet_onload == -1)
+    return cronet_onload;
+
+  if (!base::android::RegisterNativeMethods(
+          env,
+          kCronetTestsRegisteredMethods,
+          arraysize(kCronetTestsRegisteredMethods))) {
+    return -1;
+  }
+  return cronet_onload;
+}
+
+extern "C" void JNIEXPORT JNICALL JNI_OnUnLoad(JavaVM* vm, void* reserved) {

[xunjieli, 2014/09/11 22:36:22]

I think JNIEXPORT and JNICALL are not defined in cronet. 
JNI_EXPORT from base/android/jni_android.h probably is the one we want
(https://code.google.com/p/chromium/codesearch#chromium/src/base/android/jni_a...).

What does 'extern "C"' do? I was experimenting with getting rid of it, and
didn't see an effect. 

[xunjieli, 2014/09/12 13:46:19]

I still have one question about JNIEXPORT and JNI_EXPORT.

[mef, 2014/09/12 13:54:30]

I think you are right and  JNIEXPORT JNICALL are not needed (and are just empty
defines). Good news is that according to some sources JNI_OnUnLoad is never
called anyway. I'll remove those decorators.

[mef, 2014/09/12 13:59:22]

Done.

+  cronet::CronetOnUnLoad(vm, reserved);
+}
+