[Telecom] Improve hold capability signal

Add some method to the ConnectionService in order to notify the
connection changed.

Test: manually test and unit test
Bug: 66949982

Change-Id: I077902474f9af70e00a383aa269e1ae6ff9230a9

telecomm/java/android/telecom/ConnectionService.java

@@ -1382,7 +1382,7 @@ public abstract class ConnectionService extends Service {
 
         connection.setTelecomCallId(callId);
         if (connection.getState() != Connection.STATE_DISCONNECTED) {
-            addConnection(callId, connection);
+            addConnection(request.getAccountHandle(), callId, connection);
         }
 
         Uri address = connection.getAddress();
@@ -1846,6 +1846,7 @@ public abstract class ConnectionService extends Service {
                     mAdapter.setIsConferenced(connectionId, id);
                 }
             }
+            onConferenceAdded(conference);
         }
     }
 
@@ -2055,6 +2056,30 @@ public abstract class ConnectionService extends Service {
      */
     public void onConference(Connection connection1, Connection connection2) {}
 
+    /**
+     * Called when a connection is added.
+     * @hide
+     */
+    public void onConnectionAdded(Connection connection) {}
+
+    /**
+     * Called when a connection is removed.
+     * @hide
+     */
+    public void onConnectionRemoved(Connection connection) {}
+
+    /**
+     * Called when a conference is added.
+     * @hide
+     */
+    public void onConferenceAdded(Conference conference) {}
+
+    /**
+     * Called when a conference is removed.
+     * @hide
+     */
+    public void onConferenceRemoved(Conference conference) {}
+
     /**
      * Indicates that a remote conference has been created for existing {@link RemoteConnection}s.
      * When this method is invoked, this {@link ConnectionService} should create its own
@@ -2122,16 +2147,18 @@ public abstract class ConnectionService extends Service {
             // prefix for a unique incremental call ID.
             id = handle.getComponentName().getClassName() + "@" + getNextCallId();
         }
-        addConnection(id, connection);
+        addConnection(handle, id, connection);
         return id;
     }
 
-    private void addConnection(String callId, Connection connection) {
+    private void addConnection(PhoneAccountHandle handle, String callId, Connection connection) {
         connection.setTelecomCallId(callId);
         mConnectionById.put(callId, connection);
         mIdByConnection.put(connection, callId);
         connection.addConnectionListener(mConnectionListener);
         connection.setConnectionService(this);
+        connection.setPhoneAccountHandle(handle);
+        onConnectionAdded(connection);
     }
 
     /** {@hide} */
@@ -2143,6 +2170,7 @@ public abstract class ConnectionService extends Service {
             mConnectionById.remove(id);
             mIdByConnection.remove(connection);
             mAdapter.removeCall(id);
+            onConnectionRemoved(connection);
         }
     }
 
@@ -2179,6 +2207,8 @@ public abstract class ConnectionService extends Service {
             mConferenceById.remove(id);
             mIdByConference.remove(conference);
             mAdapter.removeCall(id);
+
+            onConferenceRemoved(conference);
         }
     }