Add utility methods for network type and country.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=199487948

library/core/src/main/java/com/google/android/exoplayer2/C.java

@@ -797,6 +797,45 @@ public final class C {
    */
   public static final int PRIORITY_DOWNLOAD = PRIORITY_PLAYBACK - 1000;
 
+  /** Network connection type. */
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({
+    NETWORK_TYPE_UNKNOWN,
+    NETWORK_TYPE_OFFLINE,
+    NETWORK_TYPE_WIFI,
+    NETWORK_TYPE_2G,
+    NETWORK_TYPE_3G,
+    NETWORK_TYPE_4G,
+    NETWORK_TYPE_CELLULAR_UNKNOWN,
+    NETWORK_TYPE_ETHERNET,
+    NETWORK_TYPE_OTHER
+  })
+  public @interface NetworkType {}
+  /** Unknown network type. */
+  public static final int NETWORK_TYPE_UNKNOWN = 0;
+  /** No network connection. */
+  public static final int NETWORK_TYPE_OFFLINE = 1;
+  /** Network type for a Wifi connection. */
+  public static final int NETWORK_TYPE_WIFI = 2;
+  /** Network type for a 2G cellular connection. */
+  public static final int NETWORK_TYPE_2G = 3;
+  /** Network type for a 3G cellular connection. */
+  public static final int NETWORK_TYPE_3G = 4;
+  /** Network type for a 4G cellular connection. */
+  public static final int NETWORK_TYPE_4G = 5;
+  /**
+   * Network type for cellular connections which cannot be mapped to one of {@link
+   * #NETWORK_TYPE_2G}, {@link #NETWORK_TYPE_3G}, or {@link #NETWORK_TYPE_4G}.
+   */
+  public static final int NETWORK_TYPE_CELLULAR_UNKNOWN = 6;
+  /** Network type for an Ethernet connection. */
+  public static final int NETWORK_TYPE_ETHERNET = 7;
+  /**
+   * Network type for other connections which are not Wifi or cellular (e.g. Ethernet, VPN,
+   * Bluetooth).
+   */
+  public static final int NETWORK_TYPE_OTHER = 8;
+
   /**
    * Converts a time in microseconds to the corresponding time in milliseconds, preserving
    * {@link #TIME_UNSET} and {@link #TIME_END_OF_SOURCE} values.

library/core/src/main/java/com/google/android/exoplayer2/util/Util.java

@@ -25,11 +25,14 @@ import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.graphics.Point;
+import android.net.ConnectivityManager;
+import android.net.NetworkInfo;
 import android.net.Uri;
 import android.os.Build;
 import android.os.Parcel;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
+import android.telephony.TelephonyManager;
 import android.text.TextUtils;
 import android.util.Log;
 import android.view.Display;
@@ -63,6 +66,7 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.ThreadFactory;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import org.checkerframework.checker.nullness.qual.PolyNull;
 
 /**
  * Miscellaneous utility methods.
@@ -397,8 +401,8 @@ public final class Util {
    * @param text The text to convert.
    * @return The lower case text, or null if {@code text} is null.
    */
-  public static String toLowerInvariant(String text) {
+  public static @PolyNull String toLowerInvariant(@PolyNull String text) {
-    return text == null ? null : text.toLowerCase(Locale.US);
+    return text == null ? text : text.toLowerCase(Locale.US);
   }
 
   /**
@@ -407,8 +411,8 @@ public final class Util {
    * @param text The text to convert.
    * @return The upper case text, or null if {@code text} is null.
    */
-  public static String toUpperInvariant(String text) {
+  public static @PolyNull String toUpperInvariant(@PolyNull String text) {
-    return text == null ? null : text.toUpperCase(Locale.US);
+    return text == null ? text : text.toUpperCase(Locale.US);
   }
 
   /**
@@ -1451,6 +1455,72 @@ public final class Util {
     return initialValue;
   }
 
+  /**
+   * Returns the {@link C.NetworkType} of the current network connection. {@link
+   * C#NETWORK_TYPE_UNKNOWN} will be returned if the {@code ACCESS_NETWORK_STATE} permission is not
+   * granted or the network connection type couldn't be determined.
+   *
+   * @param context A context to access the connectivity manager.
+   * @return The {@link C.NetworkType} of the current network connection, or {@link
+   *     C#NETWORK_TYPE_UNKNOWN} if the {@code ACCESS_NETWORK_STATE} permission is not granted or
+   *     {@code context} is null.
+   */
+  public static @C.NetworkType int getNetworkType(@Nullable Context context) {
+    if (context == null) {
+      return C.NETWORK_TYPE_UNKNOWN;
+    }
+    NetworkInfo networkInfo;
+    try {
+      ConnectivityManager connectivityManager =
+          (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
+      if (connectivityManager == null) {
+        return C.NETWORK_TYPE_UNKNOWN;
+      }
+      networkInfo = connectivityManager.getActiveNetworkInfo();
+    } catch (SecurityException e) {
+      // Permission ACCESS_NETWORK_STATE not granted.
+      return C.NETWORK_TYPE_UNKNOWN;
+    }
+    if (networkInfo == null || !networkInfo.isConnected()) {
+      return C.NETWORK_TYPE_OFFLINE;
+    }
+    switch (networkInfo.getType()) {
+      case ConnectivityManager.TYPE_WIFI:
+        return C.NETWORK_TYPE_WIFI;
+      case ConnectivityManager.TYPE_WIMAX:
+        return C.NETWORK_TYPE_4G;
+      case ConnectivityManager.TYPE_MOBILE:
+      case ConnectivityManager.TYPE_MOBILE_DUN:
+      case ConnectivityManager.TYPE_MOBILE_HIPRI:
+        return getMobileNetworkType(networkInfo);
+      case ConnectivityManager.TYPE_ETHERNET:
+        return C.NETWORK_TYPE_ETHERNET;
+      default: // Ethernet, VPN, Bluetooth, Dummy.
+        return C.NETWORK_TYPE_OTHER;
+    }
+  }
+
+  /**
+   * Returns the upper-case ISO 3166-1 alpha-2 country code of the current registered operator's MCC
+   * (Mobile Country Code), or the country code of the default Locale if not available.
+   *
+   * @param context A context to access the telephony service. If null, only the Locale can be used.
+   * @return The upper-case ISO 3166-1 alpha-2 country code, or an empty String if unavailable.
+   */
+  public static String getCountryCode(@Nullable Context context) {
+    if (context != null) {
+      TelephonyManager telephonyManager =
+          (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
+      if (telephonyManager != null) {
+        String countryCode = telephonyManager.getNetworkCountryIso();
+        if (!TextUtils.isEmpty(countryCode)) {
+          return toUpperInvariant(countryCode);
+        }
+      }
+    }
+    return toUpperInvariant(Locale.getDefault().getCountry());
+  }
+
   /**
    * Gets the physical size of the default display, in pixels.
    *
@@ -1545,6 +1615,36 @@ public final class Util {
     outSize.y = display.getHeight();
   }
 
+  private static @C.NetworkType int getMobileNetworkType(NetworkInfo networkInfo) {
+    switch (networkInfo.getSubtype()) {
+      case TelephonyManager.NETWORK_TYPE_EDGE:
+      case TelephonyManager.NETWORK_TYPE_GPRS:
+        return C.NETWORK_TYPE_2G;
+      case TelephonyManager.NETWORK_TYPE_1xRTT:
+      case TelephonyManager.NETWORK_TYPE_CDMA:
+      case TelephonyManager.NETWORK_TYPE_EVDO_0:
+      case TelephonyManager.NETWORK_TYPE_EVDO_A:
+      case TelephonyManager.NETWORK_TYPE_EVDO_B:
+      case TelephonyManager.NETWORK_TYPE_HSDPA:
+      case TelephonyManager.NETWORK_TYPE_HSPA:
+      case TelephonyManager.NETWORK_TYPE_HSUPA:
+      case TelephonyManager.NETWORK_TYPE_IDEN:
+      case TelephonyManager.NETWORK_TYPE_UMTS:
+      case TelephonyManager.NETWORK_TYPE_EHRPD:
+      case TelephonyManager.NETWORK_TYPE_HSPAP:
+      case TelephonyManager.NETWORK_TYPE_TD_SCDMA:
+        return C.NETWORK_TYPE_3G;
+      case TelephonyManager.NETWORK_TYPE_LTE:
+        return C.NETWORK_TYPE_4G;
+      case TelephonyManager.NETWORK_TYPE_IWLAN:
+        return C.NETWORK_TYPE_WIFI;
+      case TelephonyManager.NETWORK_TYPE_GSM:
+      case TelephonyManager.NETWORK_TYPE_UNKNOWN:
+      default: // Future mobile network types.
+        return C.NETWORK_TYPE_CELLULAR_UNKNOWN;
+    }
+  }
+
   /**
    * Allows the CRC calculation to be done byte by byte instead of bit per bit being the order
    * "most significant bit first".