refactoring Android Webview JNI_OnLoad interface

android_webview/lib/main/webview_jni_onload.cc

 // Copyright 2015 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 "android_webview/lib/main/webview_jni_onload.h"
 
 #include "android_webview/lib/main/aw_main_delegate.h"
 #include "android_webview/native/android_webview_jni_registrar.h"
 #include "base/android/jni_android.h"
 #include "base/android/jni_registrar.h"
+#include "base/bind.h"
 #include "components/navigation_interception/component_jni_registrar.h"
 #include "components/web_contents_delegate_android/component_jni_registrar.h"
+#include "content/public/app/content_jni_onload.h"
 #include "content/public/app/content_main.h"
 #include "url/url_util.h"
 
 namespace android_webview {
 
 namespace {
 
 static base::android::RegistrationMethod
     kWebViewDependencyRegisteredMethods[] = {
     { "NavigationInterception",
         navigation_interception::RegisterNavigationInterceptionJni },
     { "WebContentsDelegateAndroid",
         web_contents_delegate_android::RegisterWebContentsDelegateAndroidJni },
 };
 
-}  // namespace
-
 bool RegisterJNI(JNIEnv* env) {
   // Register JNI for components we depend on.
   if (!RegisterNativeMethods(
           env,
           kWebViewDependencyRegisteredMethods,
           arraysize(kWebViewDependencyRegisteredMethods)) ||
       !android_webview::RegisterJni(env)) {
     return false;
   }
   return true;
 }
 
 bool Init() {
   content::SetContentMainDelegate(new android_webview::AwMainDelegate());
 
   // Initialize url lib here while we are still single-threaded, in case we use
   // CookieManager before initializing Chromium (which would normally have done
   // this). It's safe to call this multiple times.
   url::Initialize();
   return true;
 }
 
+}  // namespace
+
+bool OnJNIOnLoadRegisterJNI(JavaVM* vm) {
+  // WebView uses native JNI exports; disable manual JNI registration to
+  // improve startup peformance.
+  base::android::DisableManualJniRegistration();

[Torne, 2015/03/05 18:56:09]

I think we should leave this in JNI_OnLoad, since whether it's safe to do this
or not is a property of the final linked .so. It is not automatically the case
that any binary which includes webview_jni_onload.cc is able to use native JNI
exports.

[michaelbai, 2015/03/05 19:28:53]

Will WebView always disable JNI Registration no matter what shared library it is
in?
If the shared library doesn't support native JNI export, it shouldn't include
WebView.

+
+  std::vector<base::android::RegisterCallback> register_callbacks;
+  register_callbacks.push_back(base::Bind(&RegisterJNI));
+  return content::android::OnJNIOnLoadRegisterJNI(vm, register_callbacks);
+}
+
+bool OnJNIOnLoadInit() {
+  std::vector<base::android::InitCallback> init_callbacks;
+  init_callbacks.push_back(base::Bind(&Init));
+  return content::android::OnJNIOnLoadInit(init_callbacks);
+}
+
 }  // android_webview