ui: Cleanup class/struct forward declarations

content/browser/renderer_host/input/main_thread_event_queue_browsertest.cc

Index: content/browser/renderer_host/input/main_thread_event_queue_browsertest.cc
diff --git a/content/browser/renderer_host/input/main_thread_event_queue_browsertest.cc b/content/browser/renderer_host/input/main_thread_event_queue_browsertest.cc
index 947228d53ccac1655c20c7e6c944273976e1562f..7770447f9329aef4ae0cd4f592bf4b62e5cfbeb0 100644
--- a/content/browser/renderer_host/input/main_thread_event_queue_browsertest.cc
+++ b/content/browser/renderer_host/input/main_thread_event_queue_browsertest.cc
@@ -123,6 +123,9 @@ class MainThreadEventQueueBrowserTest : public ContentBrowserTest {
 
     // Runs until we get the InputMsgAck callback.
     EXPECT_EQ(INPUT_EVENT_ACK_STATE_CONSUMED, input_msg_watcher->WaitForAck());
+    EXPECT_EQ(InputEventAckSource::MAIN_THREAD,
+              static_cast<InputEventAckSource>(
+                  input_msg_watcher->last_event_ack_source()));
 
     int mouse_move_count = 0;
     while (mouse_move_count <= 0)
@@ -160,6 +163,9 @@ class MainThreadEventQueueBrowserTest : public ContentBrowserTest {
     // Runs until we get the InputMsgAck callback.
     EXPECT_EQ(INPUT_EVENT_ACK_STATE_SET_NON_BLOCKING,
               input_msg_watcher->WaitForAck());
+    EXPECT_EQ(InputEventAckSource::COMPOSITOR_THREAD,
+              static_cast<InputEventAckSource>(
+                  input_msg_watcher->last_event_ack_source()));
 
     int touch_move_count = 0;
     while (touch_move_count <= 0)