[web_engine] Set the background color to black at view creation time.

Ensures that the view stays black until webpage style data is loaded and
parsed, by setting up a black background layer and making content
output surfaces initially transparent.

Some IWYU fixes.

Bug: 1051241
Change-Id: I22552863c1ae7cb2b7df280a4936a65445614215
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2123307
Commit-Queue: Kevin Marshall <kmarshall@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: David Dorwin <ddorwin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#755213}

fuchsia/engine/browser/frame_impl.cc

@@ -7,6 +7,7 @@
 #include <fuchsia/ui/gfx/cpp/fidl.h>
 #include <lib/sys/cpp/component_context.h>
 #include <lib/ui/scenic/cpp/view_ref_pair.h>
+#include <limits>
 
 #include "base/bind_helpers.h"
 #include "base/fuchsia/default_context.h"
@@ -23,6 +24,9 @@
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/browser/navigation_handle.h"
 #include "content/public/browser/permission_controller_delegate.h"
+#include "content/public/browser/render_view_host.h"
+#include "content/public/browser/render_widget_host.h"
+#include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/renderer_preferences_util.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/was_activated_option.mojom.h"
@@ -1024,3 +1028,20 @@ void FrameImpl::DidFinishLoad(content::RenderFrameHost* render_frame_host,
                               const GURL& validated_url) {
   context_->devtools_controller()->OnFrameLoaded(web_contents_.get());
 }
+
+void FrameImpl::RenderViewCreated(content::RenderViewHost* render_view_host) {
+  render_view_host->GetWidget()->GetView()->SetBackgroundColor(
+      SK_AlphaTRANSPARENT);
+}
+
+void FrameImpl::RenderViewReady() {
+  web_contents_->GetRenderViewHost()
+      ->GetWidget()
+      ->GetView()
+      ->SetBackgroundColor(SK_AlphaTRANSPARENT);
+
+  // Setting the background color doesn't necessarily apply it right away, so
+  // request a redraw if there is a view connected to this Frame.
+  if (window_tree_host_)
+    window_tree_host_->compositor()->ScheduleDraw();
+}

fuchsia/engine/browser/frame_impl.h

@@ -217,6 +217,8 @@ class FrameImpl : public fuchsia::web::Frame,
       content::NavigationHandle* navigation_handle) override;
   void DidFinishLoad(content::RenderFrameHost* render_frame_host,
                      const GURL& validated_url) override;
+  void RenderViewCreated(content::RenderViewHost* render_view_host) override;
+  void RenderViewReady() override;
 
   const std::unique_ptr<content::WebContents> web_contents_;
   ContextImpl* const context_;

fuchsia/engine/browser/frame_layout_manager.cc

@@ -10,10 +10,6 @@
 
 namespace {
 
-// The background color that is shown when the main window does not fully
-// fill the View.
-constexpr SkColor kLetterboxBackgroundColor = SK_ColorBLACK;
-
 // Returns a scaling factor that will allow |inset| to fit fully inside
 // |container| without clipping.
 float ProportionalScale(gfx::Size inset, gfx::Size container) {
@@ -54,8 +50,13 @@ void FrameLayoutManager::OnWindowAddedToLayout(aura::Window* child) {
     main_child_ = child;
     SetChildBoundsDirect(main_child_,
                          gfx::Rect(main_child_->parent()->bounds().size()));
-
     UpdateContentBounds();
+
+    // Make the compositor's background transparent by default.
+    main_child_->parent()->GetHost()->compositor()->SetBackgroundColor(
+        SK_AlphaTRANSPARENT);
+    main_child_->GetHost()->compositor()->SetBackgroundColor(
+        SK_AlphaTRANSPARENT);
   }
 }
 
@@ -103,7 +104,4 @@ void FrameLayoutManager::UpdateContentBounds() {
       (actual_size.height() - (render_size_override_.height() * scale)) / 2.0;
   transform.Translate(center_x_offset, center_y_offset);
   main_child_->SetTransform(transform);
-
-  main_child_->parent()->GetHost()->compositor()->SetBackgroundColor(
-      kLetterboxBackgroundColor);
 }

ui/ozone/platform/scenic/scenic_window.cc

@@ -37,7 +37,8 @@ ScenicWindow::ScenicWindow(ScenicWindowManager* window_manager,
             "chromium window"),
       node_(&scenic_session_),
       input_node_(&scenic_session_),
-      render_node_(&scenic_session_) {
+      render_node_(&scenic_session_),
+      background_node_(&scenic_session_) {
   scenic_session_.set_error_handler(
       fit::bind_member(this, &ScenicWindow::OnScenicError));
   scenic_session_.set_event_handler(
@@ -51,9 +52,28 @@ ScenicWindow::ScenicWindow(ScenicWindowManager* window_manager,
   // Add input shape.
   node_.AddChild(input_node_);
 
-  // Add rendering subtree.
+  // Add rendering subtree, rooted at Z=-2 to make room for background layers in
+  // the Z-order (lesser values are higher in the visual ordering).
+  constexpr float kRenderNodeZPosition = -2.;
+  constexpr float kBackgroundNodeZPosition = kRenderNodeZPosition + 1.;
+  render_node_.SetTranslation(0., 0., kRenderNodeZPosition);
   node_.AddChild(render_node_);
 
+  // Initialize a black background to be just behind |render_node_|.
+  scenic::Material background_color(&scenic_session_);
+  background_color.SetColor(0, 0, 0, 255);  // RGBA (0,0,0,255) = opaque black.
+  background_node_.SetMaterial(background_color);
+  scenic::Rectangle background_shape(&scenic_session_, 1., 1.);
+  background_node_.SetShape(background_shape);
+  background_node_.SetTranslation(0., 0., kBackgroundNodeZPosition);
+  node_.AddChild(background_node_);
+
+  // Render the background immediately.
+  scenic_session_.Present2(
+      /*requested_presentation_time=*/0,
+      /*requested_prediction_span=*/0,
+      [](fuchsia::scenic::scheduling::FuturePresentationTimes info) {});
+
   delegate_->OnAcceleratedWidgetAvailable(window_id_);
 }
 
@@ -223,8 +243,12 @@ void ScenicWindow::UpdateSize() {
   render_node_.SetScale(size_dips_.width(), size_dips_.height(), 1.f);
 
   // Resize input node to cover the whole surface.
-  input_node_.SetShape(scenic::Rectangle(&scenic_session_, size_dips_.width(),
-                                         size_dips_.height()));
+  scenic::Rectangle window_rect(&scenic_session_, size_dips_.width(),
+                                size_dips_.height());
+  input_node_.SetShape(window_rect);
+
+  // Resize the input and background nodes to cover the whole surface.
+  background_node_.SetShape(window_rect);
 
   // This is necessary when using vulkan because ImagePipes are presented
   // separately and we need to make sure our sizes change is committed.

ui/ozone/platform/scenic/scenic_window.h

@@ -10,6 +10,7 @@
 #include <lib/ui/scenic/cpp/resources.h>
 #include <lib/ui/scenic/cpp/session.h>
 #include <lib/ui/scenic/cpp/view_ref_pair.h>
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -117,6 +118,11 @@ class COMPONENT_EXPORT(OZONE) ScenicWindow
 
   // Node in |scenic_session_| for rendering (hit testing disabled).
   scenic::EntityNode render_node_;
+
+  // Node in |scenic_session_| for rendering a solid color, placed just behind
+  // |render_node_| in the Z order.
+  scenic::ShapeNode background_node_;
+
   std::unique_ptr<scenic::ViewHolder> surface_view_holder_;
 
   // The ratio used for translating device-independent coordinates to absolute