compositor-worker: plumb element id and mutable properties

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 ff610fc7505eb5cb88eae2596ef7f27a8ba0df42..05a473c58849e5b9c271faf54e97078d0545ce31 100644
--- a/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
+++ b/third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp
@@ -181,6 +181,24 @@ void StyleAdjuster::adjustComputedStyle(ComputedStyle& style, const ComputedStyl
         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();