compositor-worker: plumb element id and mutable properties

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 163 matching lines @@
 
         // We don't adjust the first letter style earlier because we may change the display setting in
         // adjustStyeForTagName() above.
         adjustStyleForFirstLetter(style);
 
         adjustStyleForDisplay(style, parentStyle, element ? &element->document() : 0);
     } else {
         adjustStyleForFirstLetter(style);
     }
 
+    if (element && element->hasCompositorProxy()) {
+        TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("compositor-worker"), "StyleAdjuster::adjustComputedStyle hasCompositorProxy");
+
+        style.setHasCompositorProxy(true);
+        // We could check which properties are actually proxied and only set
+        // will change on those, but there is currently little value as these
+        // have the same effect. It will also require providing a way for
+        // elements to access their associated proxies on the main thread (there
+        // is no other reason for doing this, presently).
+        style.setWillChangeScrollPosition(true);
+        Vector<CSSPropertyID> properties = style.willChangeProperties();
+        if (!properties.contains(CSSPropertyOpacity))
+            properties.append(CSSPropertyOpacity);
+        if (!properties.contains(CSSPropertyTransform))
+            properties.append(CSSPropertyTransform);
+        style.setWillChangeProperties(properties);

[enne (OOO), 2015/11/10 00:11:41]

This is what guarantees that having a compositor proxy creates a graphics layer?

[Ian Vollick, 2015/11/10 20:30:14]

Yep, that's right.

+    }
+
     // Make sure our z-index value is only applied if the object is positioned.
     if (style.position() == StaticPosition && !parentStyleForcesZIndexToCreateStackingContext(parentStyle))
         style.setHasAutoZIndex();
 
     // Auto z-index becomes 0 for the root element and transparent objects. This prevents
     // cases where objects that should be blended as a single unit end up with a non-transparent
     // object wedged in between them. Auto z-index also becomes 0 for objects that specify transforms/masks/reflections.
     if (style.hasAutoZIndex() && ((element && element->document().documentElement() == element)
         || style.hasOpacity()
         || style.hasTransformRelatedProperty()
@@ skipping 290 matching lines @@
         // We want to count vertical percentage paddings/margins on flex items because our current
         // behavior is different from the spec and we want to gather compatibility data.
         if (style.paddingBefore().hasPercent() || style.paddingAfter().hasPercent())
             UseCounter::count(document, UseCounter::FlexboxPercentagePaddingVertical);
         if (style.marginBefore().hasPercent() || style.marginAfter().hasPercent())
             UseCounter::count(document, UseCounter::FlexboxPercentageMarginVertical);
     }
 }
 
 }