Avoid a flash when the fullscreen element is sometimes resized.

The background can be painted underneath occasionally. When we have a fullscreen element indicate the backdrop's color. BUG=886544, 785001 Change-Id: I17d2533779abc68b14bc8af732f182dd32e963f0 Reviewed-on: https://chromium-review.googlesource.com/1234232 Commit-Queue: Dave Tapuska <dtapuska@chromium.org> Reviewed-by: Philip Jägenstedt <foolip@chromium.org> Cr-Commit-Position: refs/heads/master@{#593193}

Avoid a flash when the fullscreen element is sometimes resized.
The background can be painted underneath occasionally. When we have a fullscreen element indicate the backdrop's color. BUG=886544, 785001 Change-Id: I17d2533779abc68b14bc8af732f182dd32e963f0 Reviewed-on: https://chromium-review.googlesource.com/1234232 Commit-Queue: Dave Tapuska <dtapuska@chromium.org> Reviewed-by: Philip Jägenstedt <foolip@chromium.org> Cr-Commit-Position: refs/heads/master@{#593193}
5ee8b41f · Dave Tapuska · Commit Bot · ff1be83f · 5ee8b41f · 5ee8b41f
Commit 5ee8b41f authored Sep 21, 2018 by Dave Tapuska Committed by Commit Bot Sep 21, 2018
3 changed files
--- a/third_party/blink/renderer/core/exported/web_view_test.cc
+++ b/third_party/blink/renderer/core/exported/web_view_test.cc
@@ -2363,6 +2363,28 @@ TEST_F(WebViewTest, FullscreenNoResetScroll) {
  EXPECT_EQ(2100, web_view_impl->MainFrameImpl()->GetScrollOffset().height);
 }

+// Tests that background color is read from the backdrop on fullscreen.
+TEST_F(WebViewTest, FullscreenBackgroundColor) {
+  RegisterMockedHttpURLLoad("fullscreen_style.html");
+  WebViewImpl* web_view_impl =
+      web_view_helper_.InitializeAndLoad(base_url_ + "fullscreen_style.html");
+  web_view_impl->Resize(WebSize(800, 600));
+  web_view_impl->UpdateAllLifecyclePhases();
+  EXPECT_EQ(SK_ColorWHITE, web_view_impl->BackgroundColor());
+
+  // Enter fullscreen.
+  LocalFrame* frame = web_view_impl->MainFrameImpl()->GetFrame();
+  Element* element = frame->GetDocument()->getElementById("fullscreenElement");
+  ASSERT_TRUE(element);
+  std::unique_ptr<UserGestureIndicator> gesture =
+      Frame::NotifyUserActivation(frame);
+  Fullscreen::RequestFullscreen(*element);
+  web_view_impl->DidEnterFullscreen();
+  web_view_impl->UpdateAllLifecyclePhases();
+
+  EXPECT_EQ(SK_ColorYELLOW, web_view_impl->BackgroundColor());
+}
+
 class PrintWebViewClient : public FrameTestHelpers::TestWebViewClient {
 public:
  PrintWebViewClient() : print_called_(false) {}

--- a/third_party/blink/renderer/core/frame/local_frame_view.cc
+++ b/third_party/blink/renderer/core/frame/local_frame_view.cc
@@ -2151,6 +2151,18 @@ Color LocalFrameView::DocumentBackgroundColor() const {
  // background color of the LocalFrameView. This should match the color drawn
  // by ViewPainter::paintBoxDecorationBackground.
  Color result = BaseBackgroundColor();
+
+  // If we have a fullscreen element grab the fullscreen color from the
+  // backdrop.
+  if (Document* doc = frame_->GetDocument()) {
+    if (Element* element = Fullscreen::FullscreenElementFrom(*doc)) {
+      if (LayoutObject* layout_object =
+              element->PseudoElementLayoutObject(kPseudoIdBackdrop)) {
+        return result.Blend(
+            layout_object->ResolveColor(GetCSSPropertyBackgroundColor()));
+      }
+    }
+  }
  auto* layout_view = GetLayoutView();
  if (layout_view) {
    result = result.Blend(

--- a/third_party/blink/renderer/core/testing/data/fullscreen_style.html
+++ b/third_party/blink/renderer/core/testing/data/fullscreen_style.html
@@ -2,6 +2,9 @@
 <html>
  <head>
    <style>
+      ::backdrop {
+          background: yellow;
+      }
      body, html {
        height: 100%;
        margin: 0px;