Multiprocess test client: Android child process launcher rework.

base/test/android/multiprocess_test_client_service.cc

+// Copyright 2016 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 "base/test/android/multiprocess_test_client_service.h"
+
+#include "base/android/jni_array.h"
+#include "base/files/scoped_file.h"
+#include "base/logging.h"
+#include "base/native_library.h"
+#include "base/posix/global_descriptors.h"
+#include "jni/MultiprocessTestClientService_jni.h"
+
+extern int main(int argc, char** argv);
+
+namespace base {
+namespace android {
+
+bool RegisterMultiprocessTestClientServiceJni(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+// static
+void RunMain(JNIEnv* env,
+             const base::android::JavaParamRef<_jobject*>& jcaller,
+             const base::android::JavaParamRef<jobjectArray>& command_line,
+             const base::android::JavaParamRef<jintArray>& fds_to_map_ids,
+             const base::android::JavaParamRef<jintArray>& fds_to_map_fds) {
+  // Guards against process being reused.
+  // Static variables, singletons, lazy instances make running code again in the
+  // same child process difficult.
+  static bool alreadyRun = false;
+  CHECK(!alreadyRun);
+  alreadyRun = true;
+
+  std::vector<std::string> cpp_command_line;
+  AppendJavaStringArrayToStringVector(env, command_line, &cpp_command_line);
+
+  std::vector<int> fd_ids;
+  base::android::JavaIntArrayToIntVector(env, fds_to_map_ids, &fd_ids);
+  std::vector<int> fd_fds;
+  base::android::JavaIntArrayToIntVector(env, fds_to_map_fds, &fd_fds);
+  CHECK(fd_ids.size() == fd_fds.size());
+
+  std::vector<base::ScopedFD> fd_scoped_fds;
+  for (size_t i = 0; i < fd_ids.size(); i++) {
+    base::GlobalDescriptors::GetInstance()->Set(fd_ids[i], fd_fds[i]);

[Robert Sesek, 2016/12/20 20:44:34]

… and rename in here, too. This line is what made me suggest the id -> key name,
since |fd_ids| and |fd_fds| was hard to mentally parse as different variables.

[Jay Civelli, 2016/12/20 23:07:26]

Done.

+  }
+  std::vector<char*> c_command_line;
+  for (auto& entry : cpp_command_line) {
+    c_command_line.push_back(&entry[0]);
+  }
+
+  int result = main(c_command_line.size(), &c_command_line[0]);
+
+  Java_MultiprocessTestClientService_setMainReturnValue(env, jcaller, result);
+}
+
+}  // namespace android
+}  // namespace base