Implement Element.scrollIntoView for scroll-behavior: smooth.

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

+// Copyright 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.
+
+#include "public/web/WebScriptSource.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "web/WebLocalFrameImpl.h"
+#include "web/tests/sim/SimCompositor.h"
+#include "web/tests/sim/SimDisplayItemList.h"
+#include "web/tests/sim/SimRequest.h"
+#include "web/tests/sim/SimTest.h"
+
+namespace blink {
+
+namespace {
+
+class SmoothScrollTest : public SimTest {};
+
+TEST_F(SmoothScrollTest, InstantScroll) {
+  v8::HandleScope handleScope(v8::Isolate::GetCurrent());
+  webView().resize(WebSize(800, 600));
+  SimRequest request("https://example.com/test.html", "text/html");
+  loadURL("https://example.com/test.html");
+  request.complete(
+      "<div id='space' style='height: 1000px'></div>"
+      "<div id='block' style='height: 1000px'></div>");
+
+  compositor().beginFrame();
+  ASSERT_EQ(0, window().scrollY());
+  mainFrame().executeScriptAndReturnValue(
+      WebScriptSource("document.getElementById('block').scrollIntoView();"));
+
+  compositor().beginFrame();
+  ASSERT_GE(window().scrollY(), 1000);
+}
+
+TEST_F(SmoothScrollTest, SmoothScroll) {
+  v8::HandleScope handleScope(v8::Isolate::GetCurrent());
+  webView().resize(WebSize(800, 600));
+  SimRequest request("https://example.com/test.html", "text/html");
+  loadURL("https://example.com/test.html");
+  request.complete(
+      "<div id='space' style='height: 1000px'></div>"
+      "<div id='block' style='height: 1000px'></div>");
+
+  compositor().beginFrame();
+  ASSERT_EQ(0, window().scrollY());
+
+  mainFrame().executeScriptAndReturnValue(
+      WebScriptSource("document.getElementById('block').scrollIntoView("
+                      "{block: 'start', behavior: 'smooth'});"));
+  compositor().beginFrame();
+  ASSERT_LT(window().scrollY(), 100);
+
+  for (int i = 0; i < 1500; ++i) {

[bokan, 2017/03/28 16:29:53]

You can modify beginFrame to take a deltaTime so that we can just instantly jump
by x milliseconds, rather than doing this loop.

[sunyunjia, 2017/04/07 13:53:21]

Done.

+    compositor().beginFrame();
+  }
+  ASSERT_GT(window().scrollY(), 200);
+  ASSERT_LT(window().scrollY(), 1000);

[bokan, 2017/03/28 16:29:53]

Is there a reason this range is so wide? Presumably there should be no
in-determinism in this test, right?

[sunyunjia, 2017/04/07 13:53:21]

Done.

+
+  while (compositor().needsBeginFrame()) {
+    compositor().beginFrame();
+  }
+  ASSERT_GE(window().scrollY(), 1000);
+}

[bokan, 2017/03/28 16:29:53]

We should add a test for the nested case to test the queuing mechanism.

[sunyunjia, 2017/04/07 13:53:21]

Done.

+
+}  // namespace
+
+}  // namespace blink