refactoring Android Webview JNI_OnLoad interface

android_webview/lib/main/webview_jni_onload.cc

Index: android_webview/lib/main/webview_jni_onload.cc
diff --git a/android_webview/lib/main/webview_jni_onload.cc b/android_webview/lib/main/webview_jni_onload.cc
index 3e011903cb2dddcdf34012f5bc6b0b08db23c108..c41b912ef6ef8a1a88a67d18ef6faf806c3fcb2d 100644
--- a/android_webview/lib/main/webview_jni_onload.cc
+++ b/android_webview/lib/main/webview_jni_onload.cc
@@ -8,8 +8,10 @@
 #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"
 
@@ -25,8 +27,6 @@ static base::android::RegistrationMethod
         web_contents_delegate_android::RegisterWebContentsDelegateAndroidJni },
 };
 
-}  // namespace
-
 bool RegisterJNI(JNIEnv* env) {
   // Register JNI for components we depend on.
   if (!RegisterNativeMethods(
@@ -49,4 +49,22 @@ bool Init() {
   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