Add equals and hashCode method for IceCandidate class.

Bug: webrtc:11072
Change-Id: I03568c3290a49466d0f459b1de8c89afaaf020ba
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/158860
Commit-Queue: Honghai Zhang <honghaiz@webrtc.org>
Reviewed-by: Alex Glaznev <glaznev@webrtc.org>
Reviewed-by: Tommi <tommi@webrtc.org>
Reviewed-by: Qingsi Wang <qingsi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29695}

sdk/android/api/org/webrtc/IceCandidate.java

@@ -10,6 +10,8 @@
 
 package org.webrtc;
 
+import android.support.annotation.Nullable;
+import java.util.Arrays;
 import org.webrtc.PeerConnection;
 
 /**
@@ -56,4 +58,29 @@ public class IceCandidate {
   String getSdp() {
     return sdp;
   }
+
+  /** equals() checks sdpMid, sdpMLineIndex, and sdp for equality. */
+  @Override
+  public boolean equals(@Nullable Object object) {
+    if (!(object instanceof IceCandidate)) {
+      return false;
+    }
+
+    IceCandidate that = (IceCandidate) object;
+    return objectEquals(this.sdpMid, that.sdpMid) && this.sdpMLineIndex == that.sdpMLineIndex
+        && objectEquals(this.sdp, that.sdp);
+  }
+
+  @Override
+  public int hashCode() {
+    Object[] values = {sdpMid, sdpMLineIndex, sdp};
+    return Arrays.hashCode(values);
+  }
+
+  private static boolean objectEquals(Object o1, Object o2) {
+    if (o1 == null) {
+      return o2 == null;
+    }
+    return o1.equals(o2);
+  }
 }