Monitor the intersection of video and viewport.

third_party/WebKit/Source/core/dom/ElementVisibilityObserver.h

Index: third_party/WebKit/Source/core/dom/ElementVisibilityObserver.h
diff --git a/third_party/WebKit/Source/core/dom/ElementVisibilityObserver.h b/third_party/WebKit/Source/core/dom/ElementVisibilityObserver.h
index c048c2a84ef2acfe3147c12a03e784e2e8c25046..64ba35df717927d3520bd82d94d1c903c3793738 100644
--- a/third_party/WebKit/Source/core/dom/ElementVisibilityObserver.h
+++ b/third_party/WebKit/Source/core/dom/ElementVisibilityObserver.h
@@ -9,11 +9,35 @@
 #include "core/dom/IntersectionObserver.h"
 #include "platform/heap/Heap.h"
 #include "platform/heap/Member.h"
+#include "public/platform/WebRect.h"
 
 namespace blink {
 
 class Element;
 
+// Base class for ElementVisibilityObserver and
+// ElementViewportIntersectionObserver.
+class CORE_EXPORT VisibilityObserverBase
+    : public GarbageCollectedFinalized<VisibilityObserverBase> {
+  WTF_MAKE_NONCOPYABLE(VisibilityObserverBase);
+
+ public:
+  VisibilityObserverBase(Element*, const Vector<float>&);
+  virtual ~VisibilityObserverBase();
+
+  virtual void onVisibilityChanged(
+      const HeapVector<Member<IntersectionObserverEntry>>& entries) = 0;
+  void start();
+  void stop();
+
+  DECLARE_VIRTUAL_TRACE();
+
+ protected:
+  Member<Element> m_element;
+  Vector<float> m_thresholds;
+  Member<IntersectionObserver> m_intersectionObserver;
+};
+
 // ElementVisibilityObserver is a helper class to be used to track the
 // visibility of an Element in the viewport. Creating an
 // ElementVisibilityObserver is a no-op with regards to CPU cycle. The observing
@@ -24,33 +48,49 @@ class Element;
 // It is a layer meant to simplify the usage for C++ Blink code checking for the
 // visibility of an element.
 class CORE_EXPORT ElementVisibilityObserver final
-    : public GarbageCollectedFinalized<ElementVisibilityObserver> {
+    : public VisibilityObserverBase {
   WTF_MAKE_NONCOPYABLE(ElementVisibilityObserver);
 
  public:
   using VisibilityCallback = Function<void(bool), WTF::SameThreadAffinity>;
 
   ElementVisibilityObserver(Element*, std::unique_ptr<VisibilityCallback>);
-  virtual ~ElementVisibilityObserver();
-
-  void start();
-  void stop();
+  ~ElementVisibilityObserver() final;
 
   void deliverObservationsForTesting();
 
-  DECLARE_VIRTUAL_TRACE();
-
  private:
   class ElementVisibilityCallback;
 
   void onVisibilityChanged(
-      const HeapVector<Member<IntersectionObserverEntry>>&);
-
-  Member<Element> m_element;
-  Member<IntersectionObserver> m_intersectionObserver;
+      const HeapVector<Member<IntersectionObserverEntry>>&) final;
   std::unique_ptr<VisibilityCallback> m_callback;
 };
 
+// ElementViewportIntersectionObserver monitors the intersection between
+// observed element and viewport.
+// Creating an ElementViewportIntersectionObserver is a no-op with regards to
+// CPU cycle. The observing has be started by calling |start()| and can be
+// stopped with |stop()|. When creating an instance, the caller will have to
+// pass a callback taking the rootRect and the intersectRect as arguments.
+class ElementViewportIntersectionObserver final
+    : public VisibilityObserverBase {
+  WTF_MAKE_NONCOPYABLE(ElementViewportIntersectionObserver);
+
+ public:
+  using RatioChangeCallback =
+      Function<void(const WebRect&, const WebRect&), WTF::SameThreadAffinity>;
+
+  ElementViewportIntersectionObserver(Element*,
+                                      std::unique_ptr<RatioChangeCallback>);
+  ~ElementViewportIntersectionObserver() final;
+
+ private:
+  void onVisibilityChanged(
+      const HeapVector<Member<IntersectionObserverEntry>>&) final;
+  std::unique_ptr<RatioChangeCallback> m_callback;
+};
+
 }  // namespace blink
 
 #endif  // ElementVisibilityObserver_h