Generate JNI code for built in Integer class

TBR=sakal@webrtc.org

Bug: webrtc:8279
Change-Id: Ic2e5d169f11a0d4a88086d61f737f33ab9e86447
Reviewed-on: https://webrtc-review.googlesource.com/24220
Reviewed-by: Magnus Jedvert <magjed@webrtc.org>
Commit-Queue: Magnus Jedvert <magjed@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20881}

sdk/android/BUILD.gn

@@ -35,13 +35,18 @@ config("libjingle_peerconnection_jni_warnings_config") {
 
 generate_jni("generated_base_jni") {
   sources = [
-    "src/java/org/webrtc/IntegerWrapper.java",
     "src/java/org/webrtc/WebRtcClassLoader.java",
   ]
   jni_package = ""
   jni_generator_include = "//sdk/android/src/jni/jni_generator_helper.h"
 }
 
+generate_jar_jni("generated_external_classes_jni") {
+  classes = [ "java/lang/Integer.class" ]
+  jni_package = ""
+  jni_generator_include = "//sdk/android/src/jni/jni_generator_helper.h"
+}
+
 rtc_source_set("base_jni") {
   sources = [
     "src/jni/androidhistogram_jni.cc",
@@ -61,6 +66,7 @@ rtc_source_set("base_jni") {
 
   deps = [
     ":generated_base_jni",
+    ":generated_external_classes_jni",
     "../../api:libjingle_peerconnection_api",
     "../../api:optional",
     "../../rtc_base:rtc_base",
@@ -602,7 +608,6 @@ rtc_android_library("libjingle_peerconnection_java") {
     "src/java/org/webrtc/HardwareVideoDecoder.java",
     "src/java/org/webrtc/HardwareVideoEncoder.java",
     "src/java/org/webrtc/Histogram.java",
-    "src/java/org/webrtc/IntegerWrapper.java",
     "src/java/org/webrtc/JniCommon.java",
     "src/java/org/webrtc/MediaCodecUtils.java",
     "src/java/org/webrtc/NativeClassQualifiedName.java",

sdk/android/src/java/org/webrtc/IntegerWrapper.java

@@ -1,24 +0,0 @@
-/*
- *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-package org.webrtc;
-
-/** This class contains the Java glue code for JNI generation of Integer handling. */
-class IntegerWrapper {
-  @CalledByNative
-  static Integer create(int i) {
-    return Integer.valueOf(i);
-  }
-
-  @CalledByNative
-  static int getIntValue(Integer i) {
-    return i;
-  }
-}

sdk/android/src/jni/jni_helpers.cc

@@ -15,7 +15,7 @@
 #include <unistd.h>
 #include <vector>
 
-#include "sdk/android/generated_base_jni/jni/IntegerWrapper_jni.h"
+#include "sdk/android/generated_external_classes_jni/jni/Integer_jni.h"
 #include "sdk/android/src/jni/class_loader.h"
 #include "sdk/android/src/jni/classreferenceholder.h"
 
@@ -278,7 +278,7 @@ std::vector<std::string> JavaToStdVectorStrings(JNIEnv* jni, jobject list) {
 rtc::Optional<int32_t> JavaIntegerToOptionalInt(JNIEnv* jni, jobject integer) {
   if (IsNull(jni, integer))
     return rtc::nullopt;
-  return Java_IntegerWrapper_getIntValue(jni, integer);
+  return JNI_Integer::Java_Integer_intValue(jni, integer);
 }
 
 jobject JavaIntegerFromOptionalInt(JNIEnv* jni,
@@ -287,7 +287,7 @@ jobject JavaIntegerFromOptionalInt(JNIEnv* jni,
 }
 
 jobject JavaIntegerFromInt(JNIEnv* jni, int32_t i) {
-  return Java_IntegerWrapper_create(jni, i);
+  return JNI_Integer::Java_Integer_ConstructorJLI_I(jni, i);
 }
 
 // Return the (singleton) Java Enum object corresponding to |index|;