Make getEcno() public.

Test: atest CellInfoTest#verifyCellSignalStrengthWcdma
Bug: 139417139
Change-Id: Ic70af2ca0d60fbf43a929982d8b6853c7b7da049
diff --git a/api/current.txt b/api/current.txt
index 603dec2..fedd253 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -44595,6 +44595,7 @@
     method public int describeContents();
     method public int getAsuLevel();
     method public int getDbm();
+    method public int getEcNo();
     method @IntRange(from=android.telephony.CellSignalStrength.SIGNAL_STRENGTH_NONE_OR_UNKNOWN, to=android.telephony.CellSignalStrength.SIGNAL_STRENGTH_GREAT) public int getLevel();
     method public void writeToParcel(android.os.Parcel, int);
     field @NonNull public static final android.os.Parcelable.Creator<android.telephony.CellSignalStrengthWcdma> CREATOR;
diff --git a/telephony/java/android/telephony/CellSignalStrengthWcdma.java b/telephony/java/android/telephony/CellSignalStrengthWcdma.java
index cdf01da..4dc54f0 100644
--- a/telephony/java/android/telephony/CellSignalStrengthWcdma.java
+++ b/telephony/java/android/telephony/CellSignalStrengthWcdma.java
@@ -245,9 +245,12 @@
     }
 
     /**
-     * Get the Ec/No as dB
+     * Get the Ec/No (Energy per chip over the noise spectral density) as dB.
      *
-     * @hide
+     * Reference: TS 25.133 Section 9.1.2.3
+     *
+     * @return the Ec/No of the measured cell in the range [-24, 1] or
+     * {@link android.telephony.CellInfo#UNAVAILABLE UNAVAILABLE} if unavailable
      */
     public int getEcNo() {
         return mEcNo;