Updates SummarizePage test

Now that page summaries are in their own conversation turn, we need to adjust the indexes we check in the SummarizePage test.

components/ai_chat/core/browser/engine/engine_consumer_oai_unittest.cc

@@ -384,7 +384,10 @@ TEST_F(EngineConsumerOAIUnitTest, SummarizePage) {
             EXPECT_EQ(*messages[1].GetDict().Find("role"), "user");
             EXPECT_EQ(*messages[1].GetDict().Find("content"),
                       "This is the text of a web page:\n<page>\nThis is a "
-                      "page.\n</page>\n\nTell me more about this page");
+                      "page.\n</page>\n\n");
+            EXPECT_EQ(*messages[2].GetDict().Find("role"), "user");
+            EXPECT_EQ(*messages[2].GetDict().Find("content"),
+                      "Tell me more about this page");
             std::move(completed_callback)
                 .Run(EngineConsumer::GenerationResult(""));
           });