Move SetHasTouchEventHandlers from WebLayerTreeView to WebWidgetClient (14/n)

We are removing the WebLayerTreeView interface as it is redundant with
WebWidgetClient now that we always composite web contents.

More importantly this helps us Close/Restart the WebWidget parts of
WebViewImpl by not requiring plumbing 2 pointers with slightly different
lifetimes (WebLayerTreeView is created inside the Init of the
WebWidgetClient). This will help avoid a bunch of complexity in
creating WebFrameWidgets and other WebWidgets.

The HaveScrollEventHandlers() method is only used in blink_unittests
and they can get at the TestWebWidgetClient, so remove it from the
public APIs entirely.

WebPagePopups don't have scroll event handlers, and even if they did
they don't need to tell the compositor. Add a comment and a
NOTREACHED() instead of code.

R=dcheng@chromium.org

Bug: 912193
Change-Id: I5aed86e0773953428aded533df4395c29f3bd451
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1713746
Commit-Queue: danakj <danakj@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#680063}

content/renderer/compositor/layer_tree_view.cc

@@ -188,14 +188,6 @@ void LayerTreeView::SetNeedsBeginFrame() {
   layer_tree_host_->SetNeedsAnimate();
 }
 
-void LayerTreeView::SetHaveScrollEventHandlers(bool has_handlers) {
-  layer_tree_host_->SetHaveScrollEventHandlers(has_handlers);
-}
-
-bool LayerTreeView::HaveScrollEventHandlers() const {
-  return layer_tree_host_->have_scroll_event_handlers();
-}
-
 void LayerTreeView::SetLayerTreeFrameSink(
     std::unique_ptr<cc::LayerTreeFrameSink> layer_tree_frame_sink) {
   if (!layer_tree_frame_sink) {

content/renderer/compositor/layer_tree_view.h

@@ -127,8 +127,6 @@ class CONTENT_EXPORT LayerTreeView
   // blink::WebLayerTreeView implementation.
   viz::FrameSinkId GetFrameSinkId() override;
   void SetNonBlinkManagedRootLayer(scoped_refptr<cc::Layer> layer);
-  void SetHaveScrollEventHandlers(bool) override;
-  bool HaveScrollEventHandlers() const override;
   int LayerTreeId() const override;
 
   void UpdateBrowserControlsState(cc::BrowserControlsState constraints,

content/renderer/render_widget.cc

@@ -3303,6 +3303,11 @@ void RenderWidget::SetHasTouchEventHandlers(bool has_handlers) {
   Send(new WidgetHostMsg_HasTouchEventHandlers(routing_id_, has_handlers));
 }
 
+void RenderWidget::SetHaveScrollEventHandlers(bool have_handlers) {
+  layer_tree_view_->layer_tree_host()->SetHaveScrollEventHandlers(
+      have_handlers);
+}
+
 void RenderWidget::SetNeedsLowLatencyInput(bool needs_low_latency) {
   if (input_event_queue_)
     input_event_queue_->SetNeedsLowLatency(needs_low_latency);

content/renderer/render_widget.h

@@ -432,6 +432,7 @@ class CONTENT_EXPORT RenderWidget
   void RequestUnbufferedInputEvents() override;
   void SetHasPointerRawUpdateEventHandlers(bool has_handlers) override;
   void SetHasTouchEventHandlers(bool has_handlers) override;
+  void SetHaveScrollEventHandlers(bool have_handlers) override;
   void SetNeedsLowLatencyInput(bool) override;
   void SetNeedsUnbufferedInputForDebugger(bool) override;
   void AnimateDoubleTapZoomInMainFrame(const blink::WebPoint& point,

third_party/blink/public/platform/web_layer_tree_view.h

@@ -68,15 +68,12 @@ class WebLayerTreeView {
                                         bool shrink_viewport) {}
 
   // Input properties ---------------------------------------------------
-  virtual void SetHaveScrollEventHandlers(bool) {}
 
   // Returns the FrameSinkId of the widget associated with this layer tree view.
   virtual viz::FrameSinkId GetFrameSinkId() { return viz::FrameSinkId(); }
 
   // Debugging / dangerous ---------------------------------------------
 
-  virtual bool HaveScrollEventHandlers() const { return false; }
-
   virtual int LayerTreeId() const { return 0; }
 
   virtual void RequestBeginMainFrameNotExpected(bool new_state) {}

third_party/blink/public/web/web_widget_client.h

@@ -193,6 +193,9 @@ class WebWidgetClient {
   // Called to update if touch events should be sent.
   virtual void SetHasTouchEventHandlers(bool) {}
 
+  // Called to update if scroll events should be sent.
+  virtual void SetHaveScrollEventHandlers(bool) {}
+
   // Called to update whether low latency input mode is enabled or not.
   virtual void SetNeedsLowLatencyInput(bool) {}
 

third_party/blink/renderer/core/exported/web_page_popup_impl.cc

@@ -175,9 +175,8 @@ class PagePopupChromeClient final : public EmptyChromeClient {
 
   void SetHasScrollEventHandlers(LocalFrame* frame,
                                  bool has_event_handlers) override {
-    DCHECK(frame->IsMainFrame());
-    if (popup_->layer_tree_view_)
-      popup_->layer_tree_view_->SetHaveScrollEventHandlers(has_event_handlers);
+    // WebPagePopup's compositor does not handle compositor thread input (set up
+    // in RenderWidget) so there is no need to signal this.
   }
 
   void SetTouchAction(LocalFrame* frame, TouchAction touch_action) override {

third_party/blink/renderer/core/frame/frame_test_helpers.cc

@@ -672,6 +672,10 @@ void TestWebWidgetClient::InjectGestureScrollEvent(
   injected_scroll_gesture_data_.push_back(data);
 }
 
+void TestWebWidgetClient::SetHaveScrollEventHandlers(bool have_handlers) {
+  have_scroll_event_handlers_ = have_handlers;
+}
+
 void TestWebWidgetClient::SetEventListenerProperties(
     cc::EventListenerClass event_class,
     cc::EventListenerProperties properties) {

third_party/blink/renderer/core/frame/frame_test_helpers.h

@@ -210,7 +210,7 @@ class TestWebWidgetClient : public WebWidgetClient {
   explicit TestWebWidgetClient(content::LayerTreeViewDelegate* = nullptr);
   ~TestWebWidgetClient() override = default;
 
-  // WebWidgetClient:
+  // WebWidgetClient implementation.
   void ScheduleAnimation() override { animation_scheduled_ = true; }
   void SetRootLayer(scoped_refptr<cc::Layer> layer) override;
   void RegisterViewportLayers(const cc::ViewportLayers& layOAers) override;
@@ -226,6 +226,7 @@ class TestWebWidgetClient : public WebWidgetClient {
                                 ScrollGranularity granularity,
                                 cc::ElementId scrollable_area_element_id,
                                 WebInputEvent::Type injected_type) override;
+  void SetHaveScrollEventHandlers(bool) override;
   void SetEventListenerProperties(
       cc::EventListenerClass event_class,
       cc::EventListenerProperties properties) override;
@@ -235,6 +236,7 @@ class TestWebWidgetClient : public WebWidgetClient {
       override;
   void StartDeferringCommits(base::TimeDelta timeout) override;
   void StopDeferringCommits(cc::PaintHoldingCommitTrigger) override;
+  void DidMeaningfulLayout(WebMeaningfulLayout) override;
 
   content::LayerTreeView* layer_tree_view() { return layer_tree_view_; }
   cc::LayerTreeHost* layer_tree_host() {
@@ -248,7 +250,8 @@ class TestWebWidgetClient : public WebWidgetClient {
   bool AnimationScheduled() { return animation_scheduled_; }
   void ClearAnimationScheduled() { animation_scheduled_ = false; }
 
-  void DidMeaningfulLayout(WebMeaningfulLayout) override;
+  // Returns the last value given to SetHaveScrollEventHandlers().
+  bool HaveScrollEventHandlers() const { return have_scroll_event_handlers_; }
 
   int VisuallyNonEmptyLayoutCount() const {
     return visually_non_empty_layout_count_;
@@ -270,6 +273,7 @@ class TestWebWidgetClient : public WebWidgetClient {
   LayerTreeViewFactory layer_tree_view_factory_;
   Vector<InjectedScrollGestureData> injected_scroll_gesture_data_;
   bool animation_scheduled_ = false;
+  bool have_scroll_event_handlers_ = false;
   int visually_non_empty_layout_count_ = 0;
   int finished_parsing_layout_count_ = 0;
   int finished_loading_layout_count_ = 0;
@@ -365,6 +369,9 @@ class WebViewHelper {
   content::LayerTreeView* GetLayerTreeView() const {
     return test_web_widget_client_->layer_tree_view();
   }
+  TestWebWidgetClient* GetWebWidgetClient() const {
+    return test_web_widget_client_;
+  }
 
   WebLocalFrameImpl* LocalMainFrame() const;
   WebRemoteFrameImpl* RemoteMainFrame() const;

third_party/blink/renderer/core/page/chrome_client_impl.cc

@@ -1059,17 +1059,16 @@ void ChromeClientImpl::StopDeferringCommits(
 
 void ChromeClientImpl::SetHasScrollEventHandlers(LocalFrame* frame,
                                                  bool has_event_handlers) {
-  // |frame| might be null if called via TreeScopeAdopter::
-  // moveNodeToNewDocument() and the new document has no frame attached.
-  // Since a document without a frame cannot attach one later, it is safe to
-  // exit early.
+  // |frame| might be null if called via
+  // TreeScopeAdopter::MoveNodeToNewDocument() and the new document has no frame
+  // attached. Since a document without a frame cannot attach one later, it is
+  // safe to exit early.
   if (!frame)
     return;
 
-  WebFrameWidgetBase* widget =
-      WebLocalFrameImpl::FromFrame(frame)->LocalRootFrameWidget();
-  if (widget && widget->GetLayerTreeView())
-    widget->GetLayerTreeView()->SetHaveScrollEventHandlers(has_event_handlers);
+  WebWidgetClient* client =
+      WebLocalFrameImpl::FromFrame(frame)->LocalRootFrameWidget()->Client();
+  client->SetHaveScrollEventHandlers(has_event_handlers);
 }
 
 void ChromeClientImpl::SetNeedsLowLatencyInput(LocalFrame* frame,

third_party/blink/renderer/core/page/scrolling/scrolling_coordinator_test.cc

@@ -127,13 +127,8 @@ class ScrollingCoordinatorTest : public testing::Test,
 
   WebViewImpl* GetWebView() const { return helper_.GetWebView(); }
   LocalFrame* GetFrame() const { return helper_.LocalMainFrame()->GetFrame(); }
-
-  WebLayerTreeView* GetWebLayerTreeView() const {
-    return GetWebView()->LayerTreeView();
-  }
-
-  WebWidgetClient* GetWidgetClient() const {
-    return GetWebView()->WidgetClient();
+  frame_test_helpers::TestWebWidgetClient* GetWidgetClient() const {
+    return helper_.GetWebWidgetClient();
   }
 
   void LoadAhem() { helper_.LoadAhem(); }
@@ -572,7 +567,7 @@ TEST_P(ScrollingCoordinatorTest, scrollEventHandler) {
   NavigateTo(base_url_ + "scroll-event-handler.html");
   ForceFullCompositingUpdate();
 
-  ASSERT_TRUE(GetWebLayerTreeView()->HaveScrollEventHandlers());
+  ASSERT_TRUE(GetWidgetClient()->HaveScrollEventHandlers());
 }
 
 TEST_P(ScrollingCoordinatorTest, updateEventHandlersDuringTeardown) {