Initial ResizeObserver implementation

third_party/WebKit/Source/core/observer/ResizeObserverEntry.idl

Index: third_party/WebKit/Source/core/observer/ResizeObserverEntry.idl
diff --git a/third_party/WebKit/Source/core/observer/ResizeObserverEntry.idl b/third_party/WebKit/Source/core/observer/ResizeObserverEntry.idl
new file mode 100644
index 0000000000000000000000000000000000000000..c22a1a844515fc5bc42a4f05ccbe3afc518d3ea8
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+++ b/third_party/WebKit/Source/core/observer/ResizeObserverEntry.idl
@@ -0,0 +1,13 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// https://github.com/WICG/ResizeObserver
+
+[
+    RuntimeEnabled=ResizeObserver,
+] interface ResizeObserverEntry {
+    readonly attribute Element target;
+    // FIXME(atotic): should return DOMReadOnlyRect once GeometryInterfaces land
+    readonly attribute ClientRect contentRect;
+};