[Fuchsia] Process ViewAttached events on Scenic Window

This CL adds a new state to ScenicWindow that checks if the view
is attached to a rendered scene graph.

Bug: 1044802
Change-Id: Ieeb98a2bbe4d214fed302d60360dd77f0b702838
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2015675
Commit-Queue: Emircan Uysaler <emircan@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#741155}

fuchsia/engine/browser/frame_impl.cc

@@ -134,9 +134,11 @@ class WindowParentingClientImpl : public aura::client::WindowParentingClient {
 // WindowTreeHost that hosts web frames.
 class FrameWindowTreeHost : public aura::WindowTreeHostPlatform {
  public:
-  explicit FrameWindowTreeHost(ui::PlatformWindowInitProperties properties)
+  explicit FrameWindowTreeHost(ui::PlatformWindowInitProperties properties,
+                               content::WebContents* web_contents)
       : aura::WindowTreeHostPlatform(std::move(properties)),
-        window_parenting_client_(window()) {}
+        window_parenting_client_(window()),
+        web_contents_(web_contents) {}
 
   ~FrameWindowTreeHost() override = default;
 
@@ -152,8 +154,17 @@ class FrameWindowTreeHost : public aura::WindowTreeHostPlatform {
     }
   }
 
+  void OnWindowStateChanged(ui::PlatformWindowState new_state) override {
+    if (new_state == ui::PlatformWindowState::kMinimized) {
+      web_contents_->WasOccluded();
+    } else {
+      web_contents_->WasShown();
+    }
+  }
+
  private:
   WindowParentingClientImpl window_parenting_client_;
+  content::WebContents* web_contents_;
 
   DISALLOW_COPY_AND_ASSIGN(FrameWindowTreeHost);
 };
@@ -495,8 +506,8 @@ void FrameImpl::CreateView(fuchsia::ui::views::ViewToken view_token) {
       std::move(semantics_manager), std::move(accessibility_view_ref),
       web_contents_.get());
 
-  SetWindowTreeHost(
-      std::make_unique<FrameWindowTreeHost>(std::move(properties)));
+  SetWindowTreeHost(std::make_unique<FrameWindowTreeHost>(std::move(properties),
+                                                          web_contents_.get()));
 }
 
 void FrameImpl::GetNavigationController(
@@ -693,7 +704,7 @@ void FrameImpl::EnableHeadlessRendering() {
   }
 
   SetWindowTreeHost(std::make_unique<FrameWindowTreeHost>(
-      ui::PlatformWindowInitProperties()));
+      ui::PlatformWindowInitProperties(), web_contents_.get()));
 
   gfx::Rect bounds(kHeadlessWindowSize);
   if (semantics_manager_for_test_) {

ui/ozone/platform/scenic/scenic_window.cc

@@ -245,14 +245,30 @@ void ScenicWindow::OnScenicEvents(
     std::vector<fuchsia::ui::scenic::Event> events) {
   for (const auto& event : events) {
     if (event.is_gfx()) {
-      if (event.gfx().is_metrics()) {
-        if (event.gfx().metrics().node_id != node_.id())
-          continue;
-        OnViewMetrics(event.gfx().metrics().metrics);
-      } else if (event.gfx().is_view_properties_changed()) {
-        if (event.gfx().view_properties_changed().view_id != view_.id())
-          continue;
-        OnViewProperties(event.gfx().view_properties_changed().properties);
+      switch (event.gfx().Which()) {
+        case fuchsia::ui::gfx::Event::kMetrics: {
+          if (event.gfx().metrics().node_id != node_.id())
+            continue;
+          OnViewMetrics(event.gfx().metrics().metrics);
+          break;
+        }
+        case fuchsia::ui::gfx::Event::kViewPropertiesChanged: {
+          DCHECK(event.gfx().view_properties_changed().view_id == view_.id());
+          OnViewProperties(event.gfx().view_properties_changed().properties);
+          break;
+        }
+        case fuchsia::ui::gfx::Event::kViewAttachedToScene: {
+          DCHECK(event.gfx().view_attached_to_scene().view_id == view_.id());
+          OnViewAttachedChanged(true);
+          break;
+        }
+        case fuchsia::ui::gfx::Event::kViewDetachedFromScene: {
+          DCHECK(event.gfx().view_detached_from_scene().view_id == view_.id());
+          OnViewAttachedChanged(false);
+          break;
+        }
+        default:
+          break;
       }
     } else if (event.is_input()) {
       OnInputEvent(event.input());
@@ -283,6 +299,12 @@ void ScenicWindow::OnViewProperties(
     UpdateSize();
 }
 
+void ScenicWindow::OnViewAttachedChanged(bool is_view_attached) {
+  delegate_->OnWindowStateChanged(is_view_attached
+                                      ? PlatformWindowState::kNormal
+                                      : PlatformWindowState::kMinimized);
+}
+
 void ScenicWindow::OnInputEvent(const fuchsia::ui::input::InputEvent& event) {
   if (event.is_focus()) {
     delegate_->OnActivationChanged(event.focus().focused);

ui/ozone/platform/scenic/scenic_window.h

@@ -86,6 +86,7 @@ class COMPONENT_EXPORT(OZONE) ScenicWindow
   // Called from OnScenicEvents() to handle view properties and metrics changes.
   void OnViewProperties(const fuchsia::ui::gfx::ViewProperties& properties);
   void OnViewMetrics(const fuchsia::ui::gfx::Metrics& metrics);
+  void OnViewAttachedChanged(bool is_view_attached);
 
   // Called from OnScenicEvents() to handle input events.
   void OnInputEvent(const fuchsia::ui::input::InputEvent& event);