[Pix2struct] Simplify generation (#22527)

* Add model to doc tests

* Remove generate and replace by prepare_inputs_for_generation

* More fixes

* Remove print statements

* Update integration tests

* Fix generate

* Remove model from auto mapping

* Use auto processor

* Fix integration tests

* Fix test

* Add inference code snippet

* Remove is_encoder_decoder

* Update docs

* Remove notebook link

tests/models/pix2struct/test_modeling_pix2struct.py

@@ -443,24 +443,22 @@ class Pix2StructTextImageModelTest(ModelTesterMixin, unittest.TestCase):
             # signature.parameters is an OrderedDict => so arg_names order is deterministic
             arg_names = [*signature.parameters.keys()]
 
-            if model.config.is_encoder_decoder:
-                expected_arg_names = [
-                    "input_ids",
-                    "attention_mask",
-                    "decoder_input_ids",
-                    "decoder_attention_mask",
-                ]
-                expected_arg_names.extend(
-                    ["head_mask", "decoder_head_mask", "cross_attn_head_mask", "encoder_outputs"]
-                    if "head_mask" and "decoder_head_mask" and "cross_attn_head_mask" in arg_names
-                    else ["encoder_outputs"]
-                )
-                self.assertListEqual(arg_names[: len(expected_arg_names)], expected_arg_names)
-            else:
-                expected_arg_names = (
-                    ["input_ids"] if model_class != Pix2StructForConditionalGeneration else ["flattened_patches"]
-                )
-                self.assertListEqual(arg_names[:1], expected_arg_names)
+            expected_arg_names = [
+                "flattened_patches",
+                "attention_mask",
+                "decoder_input_ids",
+                "decoder_attention_mask",
+                "head_mask",
+                "decoder_head_mask",
+                "cross_attn_head_mask",
+                "encoder_outputs",
+                "past_key_values",
+                "labels",
+                "decoder_inputs_embeds",
+                "use_cache",
+            ]
+
+            self.assertListEqual(arg_names[: len(expected_arg_names)], expected_arg_names)
 
     def test_training(self):
         if not self.model_tester.is_training:
@@ -765,7 +763,7 @@ class Pix2StructIntegrationTest(unittest.TestCase):
         )
 
     def test_vqa_model(self):
-        model_id = "ybelkada/pix2struct-ai2d-base"
+        model_id = "google/pix2struct-ai2d-base"
 
         image_url = "https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/transformers/tasks/ai2d-demo.jpg"
         image = Image.open(requests.get(image_url, stream=True).raw)
@@ -784,7 +782,7 @@ class Pix2StructIntegrationTest(unittest.TestCase):
         self.assertEqual(processor.decode(predictions[0], skip_special_tokens=True), "ash cloud")
 
     def test_vqa_model_batched(self):
-        model_id = "ybelkada/pix2struct-ai2d-base"
+        model_id = "google/pix2struct-ai2d-base"
 
         image_urls = [
             "https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/transformers/tasks/ai2d-demo.jpg",