Update from https://crrev.com/333737

base/android/apk_assets.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 <jni.h>
+
+#include "base/android/apk_assets.h"
+
+#include "base/android/jni_array.h"
+#include "base/android/jni_string.h"
+#include "base/android/scoped_java_ref.h"
+#include "jni/ApkAssets_jni.h"
+
+namespace base {
+namespace android {
+
+bool RegisterApkAssets(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+int OpenApkAsset(const std::string& file_path,
+                 base::MemoryMappedFile::Region* region) {
+  // The AAssetManager API of the NDK is does not expose a method for accessing
+  // raw resources :(.
+  JNIEnv* env = base::android::AttachCurrentThread();
+  ScopedJavaLocalRef<jlongArray> jarr = Java_ApkAssets_open(
+      env,
+      base::android::GetApplicationContext(),
+      base::android::ConvertUTF8ToJavaString(env, file_path).Release());
+  std::vector<jlong> results;
+  base::android::JavaLongArrayToLongVector(env, jarr.obj(), &results);
+  CHECK_EQ(3U, results.size());
+  int fd = static_cast<int>(results[0]);
+  region->offset = results[1];
+  region->size = results[2];
+  return fd;
+}
+
+bool RegisterApkAssetWithGlobalDescriptors(base::GlobalDescriptors::Key key,
+                                           const std::string& file_path) {
+  base::MemoryMappedFile::Region region =
+      base::MemoryMappedFile::Region::kWholeFile;
+  int asset_fd = OpenApkAsset(file_path, &region);
+  if (asset_fd != -1) {
+    base::GlobalDescriptors::GetInstance()->Set(key, asset_fd, region);
+  }
+  return asset_fd != -1;
+}
+
+}  // namespace android
+}  // namespace base