Expose cellular signal strength on Android to native

net/android/java/src/org/chromium/net/AndroidCellularSignalStrength.java

Index: net/android/java/src/org/chromium/net/AndroidCellularSignalStrength.java
diff --git a/net/android/java/src/org/chromium/net/AndroidCellularSignalStrength.java b/net/android/java/src/org/chromium/net/AndroidCellularSignalStrength.java
new file mode 100644
index 0000000000000000000000000000000000000000..6dfafc759b7abab61156a54287848cd878dd750c
--- /dev/null
+++ b/net/android/java/src/org/chromium/net/AndroidCellularSignalStrength.java
@@ -0,0 +1,151 @@
+// 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.
+
+package org.chromium.net;
+
+import android.annotation.SuppressLint;
+import android.content.Context;
+import android.os.Build;
+import android.telephony.CellInfo;
+import android.telephony.CellInfoCdma;
+import android.telephony.CellInfoGsm;
+import android.telephony.CellInfoLte;
+import android.telephony.CellInfoWcdma;
+import android.telephony.CellSignalStrengthCdma;
+import android.telephony.CellSignalStrengthGsm;
+import android.telephony.CellSignalStrengthLte;
+import android.telephony.CellSignalStrengthWcdma;
+import android.telephony.TelephonyManager;
+
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+
+import java.util.List;
+
+/**
+ * This class interacts with the cellular signal strength API provided by Android.
+ */
+@JNINamespace("net::android::cellular_signal_strength")
+public class AndroidCellularSignalStrength {
+    /**
+     * True if the Android API to query the cellular signal strength is available.
+     * getAllCellInfo is only available on API Level JELLY_BEAN_MR1 and higher.
+     */
+    private static final boolean sAPIAvailable =
+            Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1;
+
+    private AndroidCellularSignalStrength() {}
+
+    /**
+     * @return RSSI (in dbM) for the currently registered cellular network. Returns {@link
+     * CellularSignalStrengthError.ERROR_NOT_SUPPORTED} if the RSSI is unavailable.
+     */
+    @SuppressWarnings("unused")
+    @SuppressLint("NewApi")
+    @CalledByNative
+    private static int getRssiDbm(Context context) {
+        List<CellInfo> cellInfos = getCellInfo(context);
+        if (cellInfos == null) {
+            return CellularSignalStrengthError.ERROR_NOT_SUPPORTED;
+        }
+
+        for (CellInfo cellInfo : cellInfos) {
+            if (cellInfo.isRegistered()) {
+                return getRssiDbm(cellInfo);
+            }
+        }
+
+        return CellularSignalStrengthError.ERROR_NOT_SUPPORTED;
+    }
+
+    /**
+     * @return the signal level (between 0 and 4, both inclusive) for the currently registered
+     * cellular network. Returns {@link CellularSignalStrengthError.ERROR_NOT_SUPPORTED} if the
+     * signal level is unavailable.
+     */
+    @SuppressWarnings("unused")
+    @SuppressLint("NewApi")
+    @CalledByNative
+    private static int getSignalLevel(Context context) {
+        List<CellInfo> cellInfos = getCellInfo(context);
+        if (cellInfos == null) {
+            return CellularSignalStrengthError.ERROR_NOT_SUPPORTED;
+        }
+
+        for (CellInfo cellInfo : cellInfos) {
+            if (cellInfo.isRegistered()) {
+                return getSignalLevel(cellInfo);
+            }
+        }
+
+        return CellularSignalStrengthError.ERROR_NOT_SUPPORTED;
+    }
+
+    /**
+    * Returns all observed cell information from all radios on the device including the primary and
+    * neighboring cells. May return null.
+    */
+    @SuppressLint("NewApi")
+    private static List<CellInfo> getCellInfo(Context context) {
+        if (!sAPIAvailable) {
+            return null;
+        }
+
+        TelephonyManager telephonyManager =
+                (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
+        if (telephonyManager == null) return null;
+
+        return telephonyManager.getAllCellInfo();
+    }
+
+    /**
+     * @return RSSI (in dbM) from {@link cellInfo}. Returns {@link
+     * CellularSignalStrengthError.ERROR_NOT_SUPPORTED} if the RSSI is
+     * unavailable.
+     */
+    @SuppressLint("NewApi")
+    private static int getRssiDbm(CellInfo cellInfo) {
+        if (cellInfo instanceof CellInfoCdma) {
+            CellSignalStrengthCdma signalStrength =
+                    ((CellInfoCdma) cellInfo).getCellSignalStrength();
+            return signalStrength.getDbm();
+        } else if (cellInfo instanceof CellInfoGsm) {
+            CellSignalStrengthGsm signalStrength = ((CellInfoGsm) cellInfo).getCellSignalStrength();
+            return signalStrength.getDbm();
+        } else if (cellInfo instanceof CellInfoLte) {
+            CellSignalStrengthLte signalStrength = ((CellInfoLte) cellInfo).getCellSignalStrength();
+            return signalStrength.getDbm();
+        } else if (cellInfo instanceof CellInfoWcdma) {
+            CellSignalStrengthWcdma signalStrength =
+                    ((CellInfoWcdma) cellInfo).getCellSignalStrength();
+            return signalStrength.getDbm();
+        }
+        return CellularSignalStrengthError.ERROR_NOT_SUPPORTED;
+    }
+
+    /**
+     * @return the signal level from {@link cellInfo}. Returns {@link
+     * CellularSignalStrengthError.ERROR_NOT_SUPPORTED} if the signal
+     * level is unavailable.
+     */
+    @SuppressLint("NewApi")
+    private static int getSignalLevel(CellInfo cellInfo) {
+        if (cellInfo instanceof CellInfoCdma) {
+            CellSignalStrengthCdma signalStrength =
+                    ((CellInfoCdma) cellInfo).getCellSignalStrength();
+            return signalStrength.getLevel();
+        } else if (cellInfo instanceof CellInfoGsm) {
+            CellSignalStrengthGsm signalStrength = ((CellInfoGsm) cellInfo).getCellSignalStrength();
+            return signalStrength.getLevel();
+        } else if (cellInfo instanceof CellInfoLte) {
+            CellSignalStrengthLte signalStrength = ((CellInfoLte) cellInfo).getCellSignalStrength();
+            return signalStrength.getLevel();
+        } else if (cellInfo instanceof CellInfoWcdma) {
+            CellSignalStrengthWcdma signalStrength =
+                    ((CellInfoWcdma) cellInfo).getCellSignalStrength();
+            return signalStrength.getLevel();
+        }
+        return CellularSignalStrengthError.ERROR_NOT_SUPPORTED;
+    }
+}