Expose cellular signal strength on Android to native

net/android/cellular_signal_strength.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 "net/android/cellular_signal_strength.h"
+
+#include "base/android/context_utils.h"
+#include "jni/AndroidCellularSignalStrength_jni.h"
+
+namespace net {
+
+namespace android {
+
+namespace cellular_signal_strength {
+
+// GENERATED_JAVA_ENUM_PACKAGE: org.chromium.net
+enum CellularSignalStrengthError {
+  // Value returned by CellularSignalStrength APIs when a valid value is
+  // unavailable. This value is same as INT32_MIN, but the following code uses
+  // the explicit value of INT32_MIN so that the auto-generated Java enums work
+  // correctly.
+  ERROR_NOT_SUPPORTED = -2147483648,
+};
+
+static_assert(
+    INT32_MIN == ERROR_NOT_SUPPORTED,
+    "CellularSignalStrengthError.ERROR_NOT_SUPPORTED has unexpected value");
+
+bool GetSignalStrengthDbm(int32_t* signal_strength_dbm) {
+  int32_t signal_strength_dbm_tmp =
+      Java_AndroidCellularSignalStrength_getSignalStrengthDbm(
+          base::android::AttachCurrentThread(),
+          base::android::GetApplicationContext());
+  if (signal_strength_dbm_tmp == ERROR_NOT_SUPPORTED)
+    return false;
+
+  *signal_strength_dbm = signal_strength_dbm_tmp;
+  return true;
+}
+
+bool GetSignalStrengthLevel(int32_t* signal_strength_level) {
+  int32_t signal_strength_level_tmp =
+      Java_AndroidCellularSignalStrength_getSignalStrengthLevel(
+          base::android::AttachCurrentThread(),
+          base::android::GetApplicationContext());
+  if (signal_strength_level_tmp == ERROR_NOT_SUPPORTED)
+    return false;
+
+  *signal_strength_level = signal_strength_level_tmp;
+  return true;
+}
+
+bool Register(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+}  // namespace cellular_signal_strength
+
+}  // namespace android
+
+}  // namespace net