IntersectionObserver: discard notifications upon disconnect().

third_party/WebKit/Source/web/tests/IntersectionObserverTest.cpp

 // 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.
 
 #include "core/dom/IntersectionObserver.h"
 
 #include "core/dom/IntersectionObserverCallback.h"
 #include "core/dom/IntersectionObserverInit.h"
 #include "core/frame/FrameView.h"
 #include "platform/testing/UnitTestHelpers.h"
@@ skipping 109 matching lines @@
       ScrollOffset(0, 300), ProgrammaticScroll);
   compositor().beginFrame();
   testing::runPendingTasks();
   EXPECT_EQ(observerCallback->callCount(), 2);
   document().resumeScheduledTasks();
   EXPECT_EQ(observerCallback->callCount(), 2);
   testing::runPendingTasks();
   EXPECT_EQ(observerCallback->callCount(), 3);
 }
 
+TEST_F(IntersectionObserverTest, DisconnectClearsNotifications) {
+  webView().resize(WebSize(800, 600));
+  SimRequest mainResource("https://example.com/", "text/html");
+  loadURL("https://example.com/");
+  mainResource.complete(
+      "<div id='leading-space' style='height: 700px;'></div>"
+      "<div id='target'></div>"
+      "<div id='trailing-space' style='height: 700px;'></div>");
+
+  IntersectionObserverInit observerInit;
+  DummyExceptionStateForTesting exceptionState;
+  TestIntersectionObserverCallback* observerCallback =
+      new TestIntersectionObserverCallback(document());
+  IntersectionObserver* observer = IntersectionObserver::create(
+      observerInit, *observerCallback, exceptionState);
+  ASSERT_FALSE(exceptionState.hadException());
+
+  Element* target = document().getElementById("target");
+  ASSERT_TRUE(target);
+  observer->observe(target, exceptionState);
+
+  compositor().beginFrame();
+  testing::runPendingTasks();
+  EXPECT_EQ(observerCallback->callCount(), 1);
+
+  // If disconnect() is called while an observer has unsent notifications,
+  // those notifications should be discarded.
+  document().view()->layoutViewportScrollableArea()->setScrollOffset(
+      ScrollOffset(0, 300), ProgrammaticScroll);
+  compositor().beginFrame();
+  observer->disconnect();
+  testing::runPendingTasks();
+  EXPECT_EQ(observerCallback->callCount(), 1);
+}
+
 }  // namespace blink