Implement Element.scrollIntoView for scroll-behavior: smooth.

third_party/WebKit/Source/platform/scroll/ProgrammaticScrollCoordinator.h

Index: third_party/WebKit/Source/platform/scroll/ProgrammaticScrollCoordinator.h
diff --git a/third_party/WebKit/Source/platform/scroll/ProgrammaticScrollCoordinator.h b/third_party/WebKit/Source/platform/scroll/ProgrammaticScrollCoordinator.h
new file mode 100644
index 0000000000000000000000000000000000000000..34cd9612ebbda30dd370c614fd8225e29366bfa5
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+++ b/third_party/WebKit/Source/platform/scroll/ProgrammaticScrollCoordinator.h
@@ -0,0 +1,46 @@
+// Copyright (c) 2017 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.
+#ifndef ProgrammaticScrollCoordinator_h
+#define ProgrammaticScrollCoordinator_h
+
+#include <utility>
+#include <vector>
+#include "platform/scroll/ProgrammaticScrollAnimatorClient.h"
+#include "platform/scroll/ScrollTypes.h"
+
+namespace blink {
+
+class ScrollableArea;
+
+class PLATFORM_EXPORT ProgrammaticScrollCoordinator
+    : public ProgrammaticScrollAnimatorClient {
+ public:
+  static ProgrammaticScrollCoordinator* create();
+
+  ~ProgrammaticScrollCoordinator();
+
+  // Add a scroll offset animation to the back of a queue.
+  void queueAnimation(ScrollableArea*, ScrollOffset);
+
+  // Run the animation at the back of the queue and sets itself as a client
+  // of ProgrammaticScrollAnimator to receive finish notification.
+  void runQueuedAnimations();
+
+  // Pop the back of the queue and run the next animation in the queue.
+  void notifyAnimationFinished();
+
+  // Abort the currently running anmation and all the animations in the queue.
+  void abortAnimations();
+
+ protected:
+  explicit ProgrammaticScrollCoordinator();
+
+ private:
+  typedef std::pair<Member<ScrollableArea>, ScrollOffset> ScrollerAndOffsetPair;
+  std::vector<ScrollerAndOffsetPair> m_queue;
+};
+
+}  // namespace blink
+
+#endif  // ProgrammaticScrollCoordinator_h