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 cffe90e1a6a699f5bde5aa09d48f237edde15443..83562d9e6ab7fa8ec6e3835b2d74f6ae543441ae 100644
--- a/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
+++ b/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
@@ -34,6 +34,8 @@
 #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"
@@ -44,6 +46,7 @@
 #include "core/html/HTMLTextAreaElement.h"
 #include "core/layout/LayoutReplaced.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"
@@ -177,6 +180,19 @@ void StyleAdjuster::adjustComputedStyle(ComputedStyle& style, const ComputedStyl
         adjustStyleForFirstLetter(style);
 
         adjustStyleForDisplay(style, parentStyle, e ? &e->document() : 0);
+
+        if (e) {
+            if (Fullscreen::isActiveFullScreenElement(*e)) {

[esprehn, 2015/09/24 20:17:01]

don't double nest, so this should be:

if (e && Fullscreen::isActiveFullScreenElement(*e)) {
  ...
}

[dsinclair, 2015/09/28 17:14:58]

Done.

+                // 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
+                IntSize viewportSize = e->document().page()->frameHost().visualViewport().size();
+                style.setWidth(Length(viewportSize.width(), Fixed));
+                style.setHeight(Length(viewportSize.height(), Fixed));

[esprehn, 2015/09/24 20:17:01]

this seems bad, what if I resize my window? I don't think this is the right
layer for this. I think you need to do it inside LayoutView?

[dsinclair, 2015/09/28 17:14:58]

So, override styleDidChange on LayoutView, get the fullscreen element with
Fullscreen::fullscreenElementFrom(document()) and set a new style on that
element changing the width and height?

+            }
+        }
     } else {
         adjustStyleForFirstLetter(style);
     }