Reland "Convert WidgetMsg_WaitForNextFrameForTest to mojo"

This is a reland of 75391394.

Reason for reland:
- Fixed a flaky test failures in crrev.com/c/2309317
- No changes in this CL between original & reland.

Original change's description:
> Convert WidgetMsg_WaitForNextFrameForTest to mojo
>
> This CL uses VisualStateRequest Mojo API in FrameWidget mojo interface
> introduced at https://crrev.com/c/2178480 since
> WidgetMsg_WaitForNextFrameForTest has the same implementation with
> VisualStateRequest Mojo API notifying that the frame swap has occurred.
>
> Bug: 1071588
> Change-Id: If317b98320ec3fb85fcf7a5d1e39f0fa202d4cde
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2216145
> Commit-Queue: Miyoung Shin <myid.shin@igalia.com>
> Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
> Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#789910}

Bug: 1071588
Change-Id: I7ade2819495cddf87862054095db361e0511dcf5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2309497
Commit-Queue: Miyoung Shin <myid.shin@igalia.com>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/heads/master@{#793839}

content/common/widget_messages.h

@@ -71,12 +71,6 @@ IPC_MESSAGE_ROUTED0(WidgetMsg_SetBounds_ACK)
 IPC_MESSAGE_ROUTED1(WidgetMsg_SetViewportIntersection,
                     blink::ViewportIntersectionState /* intersection_state */)
 
-
-// Sent by the browser to synchronize with the next compositor frame by
-// requesting an ACK be queued. Used only for tests.
-IPC_MESSAGE_ROUTED1(WidgetMsg_WaitForNextFrameForTests,
-                    int /* main_frame_thread_observer_routing_id */)
-
 //
 // Renderer -> Browser Messages.
 //
@@ -105,7 +99,4 @@ IPC_MESSAGE_ROUTED2(WidgetHostMsg_FrameSwapMessages,
 // Close message.
 IPC_MESSAGE_CONTROL1(WidgetHostMsg_Close_ACK, int /* old_route_id */)
 
-// Sent in reply to WidgetMsg_WaitForNextFrameForTests.
-IPC_MESSAGE_ROUTED0(WidgetHostMsg_WaitForNextFrameForTests_ACK)
-
 #endif  //  CONTENT_COMMON_WIDGET_MESSAGES_H_

content/public/test/browser_test_utils.cc

@@ -2635,40 +2635,25 @@ void RenderFrameSubmissionObserver::OnLocalSurfaceIdChanged(
 MainThreadFrameObserver::MainThreadFrameObserver(
     RenderWidgetHost* render_widget_host)
     : render_widget_host_(render_widget_host),
-      routing_id_(render_widget_host_->GetProcess()->GetNextRoutingID()) {
-  // TODO(lfg): We should look into adding a way to observe RenderWidgetHost
-  // messages similarly to what WebContentsObserver can do with RFH and RVW.
-  render_widget_host_->GetProcess()->AddRoute(routing_id_, this);
-}
+      routing_id_(render_widget_host_->GetProcess()->GetNextRoutingID()) {}
 
-MainThreadFrameObserver::~MainThreadFrameObserver() {
-  render_widget_host_->GetProcess()->RemoveRoute(routing_id_);
-}
+MainThreadFrameObserver::~MainThreadFrameObserver() = default;
 
 void MainThreadFrameObserver::Wait() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  render_widget_host_->Send(new WidgetMsg_WaitForNextFrameForTests(
-      render_widget_host_->GetRoutingID(), routing_id_));
+  static_cast<RenderWidgetHostImpl*>(render_widget_host_)
+      ->InsertVisualStateCallback(base::BindOnce(&MainThreadFrameObserver::Quit,
+                                                 base::Unretained(this)));
   base::RunLoop run_loop;
   quit_closure_ = run_loop.QuitClosure();
   run_loop.Run();
 }
 
-void MainThreadFrameObserver::Quit() {
+void MainThreadFrameObserver::Quit(bool) {
   if (quit_closure_)
     std::move(quit_closure_).Run();
 }
 
-bool MainThreadFrameObserver::OnMessageReceived(const IPC::Message& msg) {
-  if (msg.type() == WidgetHostMsg_WaitForNextFrameForTests_ACK::ID &&
-      msg.routing_id() == routing_id_) {
-    GetUIThreadTaskRunner({})->PostTask(
-        FROM_HERE,
-        base::BindOnce(&MainThreadFrameObserver::Quit, base::Unretained(this)));
-  }
-  return true;
-}
-
 InputMsgWatcher::InputMsgWatcher(RenderWidgetHost* render_widget_host,
                                  blink::WebInputEvent::Type type)
     : render_widget_host_(render_widget_host),

content/public/test/browser_test_utils.h

@@ -1308,20 +1308,17 @@ class RenderFrameSubmissionObserver
 // So while the ACK can arrive before a CompositorFrame submission occurs. The
 // processing does not occur until after the FrameToken for that frame
 // submission arrives to the main thread.
-class MainThreadFrameObserver : public IPC::Listener {
+class MainThreadFrameObserver {
  public:
   explicit MainThreadFrameObserver(RenderWidgetHost* render_widget_host);
-  ~MainThreadFrameObserver() override;
+  ~MainThreadFrameObserver();
 
   // Synchronizes the browser main thread with the renderer main thread and impl
   // thread.
   void Wait();
 
-  // Overridden IPC::Listener methods.
-  bool OnMessageReceived(const IPC::Message& msg) override;
-
  private:
-  void Quit();
+  void Quit(bool);
 
   RenderWidgetHost* render_widget_host_;
   base::OnceClosure quit_closure_;

content/renderer/render_widget.cc

@@ -435,8 +435,6 @@ bool RenderWidget::OnMessageReceived(const IPC::Message& message) {
     IPC_MESSAGE_HANDLER(WidgetMsg_SetBounds_ACK, OnRequestSetBoundsAck)
     IPC_MESSAGE_HANDLER(WidgetMsg_SetViewportIntersection,
                         OnSetViewportIntersection)
-    IPC_MESSAGE_HANDLER(WidgetMsg_WaitForNextFrameForTests,
-                        OnWaitNextFrameForTests)
     IPC_MESSAGE_HANDLER(DragMsg_TargetDragEnter, OnDragTargetDragEnter)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
@@ -1651,13 +1649,6 @@ void RenderWidget::UnregisterRenderFrame(RenderFrameImpl* frame) {
   render_frames_.RemoveObserver(frame);
 }
 
-void RenderWidget::OnWaitNextFrameForTests(
-    int main_frame_thread_observer_routing_id) {
-  // Sends an ACK to the browser process during the next compositor frame.
-  QueueMessage(std::make_unique<WidgetHostMsg_WaitForNextFrameForTests_ACK>(
-      main_frame_thread_observer_routing_id));
-}
-
 const blink::ScreenInfo& RenderWidget::GetOriginalScreenInfo() const {
   if (device_emulator_)
     return device_emulator_->original_screen_info();

content/renderer/render_widget.h

@@ -479,7 +479,6 @@ class CONTENT_EXPORT RenderWidget
                          const gfx::PointF& screen_point,
                          blink::WebDragOperation drag_operation);
   void OnOrientationChange();
-  void OnWaitNextFrameForTests(int routing_id);
 
   // Sets the "hidden" state of this widget.  All modification of is_hidden_
   // should use this method so that we can properly inform the RenderThread of