Cook onion in oil in a 12-inch heavy skillet over medium-low heat, stirring occasionally, until beginning to soften, about 5 minutes. Increase heat to medium, then add garlic and tomato and cook, stirring, until tomatoes begin to break down, 3 to 5 minutes. Stir in olives, capers, raisins, pine nuts, fruit, ginger, thyme, marjoram, ground cinnamon and peppercorns, and 1 tsp salt and cook, stirring, until fruit is slightly softened, about 10 minutes (add 1/4 to 1/2 cup water if mixture is dry). Remove from heat and stir in chicken, enough stock to moisten filling, and salt to taste. Cool completely.