Reland "Implement FullScreen using top layer."

third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp

Index: third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
diff --git a/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp b/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
index b4797ba5d2765b6d63aa8673f81aa273a2180e8b..decc9ec044aa44846002364f93fdf501588327d0 100644
--- a/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
+++ b/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
@@ -33,15 +33,19 @@
 #include "core/dom/ContainerNode.h"
 #include "core/dom/Document.h"
 #include "core/dom/Element.h"
+#include "core/dom/Fullscreen.h"
+#include "core/frame/FrameHost.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/Settings.h"
 #include "core/frame/UseCounter.h"
+#include "core/frame/VisualViewport.h"
 #include "core/html/HTMLIFrameElement.h"
 #include "core/html/HTMLInputElement.h"
 #include "core/html/HTMLPlugInElement.h"
 #include "core/html/HTMLTableCellElement.h"
 #include "core/html/HTMLTextAreaElement.h"
 #include "core/layout/LayoutTheme.h"
+#include "core/page/Page.h"
 #include "core/style/ComputedStyle.h"
 #include "core/style/ComputedStyleConstants.h"
 #include "core/svg/SVGSVGElement.h"
@@ -173,6 +177,17 @@ void StyleAdjuster::adjustComputedStyle(ComputedStyle& style, const ComputedStyl
         // https://drafts.csswg.org/css-containment/#containment-paint
         if (style.containsPaint() && style.display() == INLINE)
             style.setDisplay(BLOCK);
+
+        if (element && Fullscreen::isActiveFullScreenElement(*element)) {
+            // We need to size the fullscreen element to the inner viewport and not to the
+            // outer viewport (what percentage would do). Unfortunately CSS can't handle
+            // that as we don't expose the inner viewport information.
+            //
+            // TODO(dsinclair): We should find a way to get this standardized. crbug.com/534924

[foolip, 2016/06/29 20:11:00]

dsinclair@, can you fill me in about the purpose of this? Is there any
connection to https://bugs.chromium.org/p/chromium/issues/detail?id=543946 and
https://github.com/whatwg/fullscreen/issues/19 where the question is whether
top-layer should end up on top of scrollbars?

[dsinclair, 2016/06/29 20:14:47]

I'm not sure if this is what causes the scrollbar bug or not, I'm not too
familiar with the viewport stuff. The TODO was that we, preferrably, want a way
for CSS to expose the inner viewport instead of forcing it here.

[foolip, 2016/06/30 14:33:24]

I tried reverting this and running test to understand what the difference is,
but no tests failed :)

Is the visual viewport the pinch zoom viewport, or something else? There are
some tricks in FullscreenController to save and restore scale and
scroll/viewport offsets, is this related?

[dsinclair, 2016/07/06 13:32:31]

I was never really clear on viewport. There is an inner and outer viewport used
for pinch-zoom. I'm not sure how those relate to the visual viewport, if at all.
You could try asking bokan@ as he did a lot of viewport work.

[foolip, 2016/07/06 14:14:51]

Thanks, I'll do that if I can't figure this out.

+            IntSize viewportSize = element->document().page()->frameHost().visualViewport().size();
+            style.setWidth(Length(viewportSize.width(), Fixed));
+            style.setHeight(Length(viewportSize.height(), Fixed));
+        }
     } else {
         adjustStyleForFirstLetter(style);
     }