IntersectionObserver: second cut.

third_party/WebKit/Source/core/dom/IntersectionObserver.idl

Index: third_party/WebKit/Source/core/dom/IntersectionObserver.idl
diff --git a/third_party/WebKit/Source/core/dom/IntersectionObserver.idl b/third_party/WebKit/Source/core/dom/IntersectionObserver.idl
new file mode 100644
index 0000000000000000000000000000000000000000..b29c890680bf711af58796971ce6b76f0a9a04b4
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+++ b/third_party/WebKit/Source/core/dom/IntersectionObserver.idl
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+// Copyright 2015 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.
+
+// http://w3c.github.io/performance-timeline/#idl-def-PerformanceObserverCallback
+callback IntersectionObserverCallback = void (sequence<IntersectionObserverEntry> entries, IntersectionObserver observer);
+
+// TODO: Update the doc link when the spec has an official home.
+// https://github.com/slightlyoff/IntersectionObserver
+[
+    CustomConstructor(IntersectionObserverCallback callback, IntersectionObserverInit options),
+    RuntimeEnabled=IntersectionObserver,
+    GarbageCollected,
+] interface IntersectionObserver {
+    [RaisesException] void observe(Element target);
+    [RaisesException] void unobserve(Element target);
+    void disconnect();
+    sequence<IntersectionObserverEntry> takeRecords();
+};