Add onBindClient for testing

Add an overrideable method in ConnectionService that gets called when
telecom binds, since onBind is final and it's unsafe to make not-final.

Bug: 181057509
Test: atest CtsTelecomTestCases
Change-Id: I80088185402789fec499b8659ca8b74bcec05748

core/api/test-current.txt

@@ -1600,6 +1600,10 @@ package android.telecom {
     method @NonNull public android.telecom.ConnectionRequest.Builder setVideoState(int);
   }
 
+  public abstract class ConnectionService extends android.app.Service {
+    method public void onBindClient(@Nullable android.content.Intent);
+  }
+
 }
 
 package android.telephony {

telecomm/java/android/telecom/ConnectionService.java

@@ -20,6 +20,7 @@ import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.annotation.SdkConstant;
 import android.annotation.SystemApi;
+import android.annotation.TestApi;
 import android.app.Service;
 import android.content.ComponentName;
 import android.content.Intent;
@@ -1887,6 +1888,7 @@ public abstract class ConnectionService extends Service {
     /** {@inheritDoc} */
     @Override
     public final IBinder onBind(Intent intent) {
+        onBindClient(intent);
         return mBinder;
     }
 
@@ -1897,6 +1899,13 @@ public abstract class ConnectionService extends Service {
         return super.onUnbind(intent);
     }
 
+    /**
+     * Used for testing to let the test suite know when the connection service has been bound.
+     * @hide
+     */
+    @TestApi
+    public void onBindClient(@Nullable Intent intent) {
+    }
 
     /**
      * This can be used by telecom to either create a new outgoing conference call or attach