[Android] Support startup histogram.

chrome/browser/android/uma_utils.cc

+// Copyright 2013 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 "chrome/browser/android/uma_utils.h"
+
+#include "jni/UmaUtils_jni.h"
+
+namespace chrome {
+namespace android {
+
+base::Time GetMainEntryPointTime() {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  int64 startTimeUnixMs = Java_UmaUtils_getMainEntryPointTime(env);
+  return base::Time::UnixEpoch() +
+         base::TimeDelta::FromMilliseconds(startTimeUnixMs);
+}
+
+bool RegisterStartupMetricUtils(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+}  // namespace android
+}  // namespace chrome