[not for review - epic CL] Adding Elastic+Momentum+Layered scrolling to views::ScrollView

ui/views/controls/scroll_view_unittest.cc

 // Copyright (c) 2012 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 "ui/views/controls/scroll_view.h"
 
 #include "base/macros.h"
+#include "base/run_loop.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/views/border.h"
+#include "ui/views/controls/scrollbar/base_scroll_bar_thumb.h"
+#include "ui/views/controls/scrollbar/native_scroll_bar.h"
+#include "ui/views/controls/scrollbar/native_scroll_bar_views.h"
 #include "ui/views/controls/scrollbar/overlay_scroll_bar.h"
 #include "ui/views/test/test_views.h"
+#include "ui/views/test/widget_test.h"
 
 #if defined(OS_MACOSX)
 #include "ui/base/test/scoped_preferred_scroller_style_mac.h"
 #endif
 
+enum ScrollBarOrientation { HORIZONTAL, VERTICAL };
+
 namespace views {
+namespace test {
+
+class ScrollViewTestApi {
+ public:
+  explicit ScrollViewTestApi(ScrollView* scroll_view)
+      : scroll_view_(scroll_view) {}
+
+  BaseScrollBar* GetBaseScrollBar(ScrollBarOrientation orientation) {
+    ScrollBar* scroll_bar = orientation == VERTICAL ? scroll_view_->vert_sb_
+                                                    : scroll_view_->horiz_sb_;
+    if (scroll_bar->GetClassName() == NativeScrollBar::kViewClassName) {
+      return static_cast<NativeScrollBarViews*>(
+          static_cast<NativeScrollBar*>(scroll_bar)->native_wrapper_);
+    }
+    return static_cast<BaseScrollBar*>(scroll_bar);
+  }
+
+  const base::Timer& GetScrollBarTimer(ScrollBarOrientation orientation) {
+    return GetBaseScrollBar(orientation)->repeater_.timer_for_testing();
+  }
+
+  BaseScrollBarThumb* GetScrollBarThumb(ScrollBarOrientation orientation) {
+    return GetBaseScrollBar(orientation)->thumb_;
+  }
+
+  gfx::Point IntegralViewOffset() {
+    return gfx::Point() - gfx::ScrollOffsetToFlooredVector2d(CurrentOffset());
+  }
+
+  gfx::ScrollOffset CurrentOffset() { return scroll_view_->CurrentOffset(); }
+
+  View* corner_view() { return scroll_view_->corner_view_; }
+  View* contents_viewport() { return scroll_view_->contents_viewport_; }
+
+ private:
+  ScrollView* scroll_view_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScrollViewTestApi);
+};
+
+}  // namespace test
 
 namespace {
 
 const int kWidth = 100;
 const int kMinHeight = 50;
 const int kMaxHeight = 100;
 
-enum ScrollBarOrientation { HORIZONTAL, VERTICAL };
-
 // View implementation that allows setting the preferred size.
 class CustomView : public View {
  public:
   CustomView() {}
 
   void SetPreferredSize(const gfx::Size& size) {
     preferred_size_ = size;
     PreferredSizeChanged();
   }
 
@@ skipping 23 matching lines @@
                                    ? scroll_view.horizontal_scroll_bar()
                                    : scroll_view.vertical_scroll_bar();
   if (should_be_visible) {
     ASSERT_TRUE(scrollbar);
     EXPECT_TRUE(scrollbar->visible());
   } else {
     EXPECT_TRUE(!scrollbar || !scrollbar->visible());
   }
 }
 
+ui::MouseEvent TestLeftMouseAt(const gfx::Point& location, ui::EventType type) {
+  return ui::MouseEvent(type, location, location, base::TimeTicks(),
+                        ui::EF_LEFT_MOUSE_BUTTON, ui::EF_LEFT_MOUSE_BUTTON);
+}
+
 }  // namespace
 
+using test::ScrollViewTestApi;
+
+// Test harness that includes a Widget to help test ui::Event handling.
+class WidgetScrollViewTest : public test::WidgetTest {
+ public:
+  const int kDefaultHeight = 100;
+  const int kDefaultWidth = 100;
+
+  WidgetScrollViewTest() {
+#if defined(OS_MACOSX)
+    // Disable scrollbar hiding (i.e. disable overlay scrollbars) by default.
+    scroller_style_.reset(new ui::test::ScopedPreferredScrollerStyle(false));
+#endif
+  }
+
+  // Adds a ScrollView with a contents view of the given |size| and does layout.
+  ScrollView* AddScrollViewWithContentSize(const gfx::Size& contents_size) {
+    const gfx::Rect default_bounds(50, 50, kDefaultWidth, kDefaultHeight);
+    widget_ = CreateTopLevelFramelessPlatformWidget();
+
+    ScrollView* scroll_view = new ScrollView();
+    View* contents = new View;
+    scroll_view->SetContents(contents);
+    contents->SetSize(contents_size);
+
+    widget_->SetBounds(default_bounds);
+    widget_->Show();
+
+    widget_->SetContentsView(scroll_view);
+    scroll_view->Layout();
+
+    // Ensure the Compositor has committed layer changes before attempting to
+    // use them for impl-side scrolling.
+    base::RunLoop().RunUntilIdle();
+    return scroll_view;
+  }
+
+  // testing::Test:
+  void TearDown() override {
+    if (widget_)
+      widget_->CloseNow();
+    WidgetTest::TearDown();
+  }
+
+ private:
+  Widget* widget_ = nullptr;
+
+#if defined(OS_MACOSX)
+  std::unique_ptr<ui::test::ScopedPreferredScrollerStyle> scroller_style_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(WidgetScrollViewTest);
+};
+
 // Verifies the viewport is sized to fit the available space.
 TEST(ScrollViewTest, ViewportSizedToFit) {
   ScrollView scroll_view;
+  ScrollViewTestApi test_api(&scroll_view);
   View* contents = new View;
   scroll_view.SetContents(contents);
   scroll_view.SetBoundsRect(gfx::Rect(0, 0, 100, 100));
   scroll_view.Layout();
-  EXPECT_EQ("0,0 100x100", contents->parent()->bounds().ToString());
+  EXPECT_EQ("0,0 100x100", test_api.contents_viewport()->bounds().ToString());
 }
 
 // Verifies the scrollbars are added as necessary.
 // If on Mac, test the non-overlay scrollbars.
 TEST(ScrollViewTest, ScrollBars) {
 #if defined(OS_MACOSX)
   ui::test::ScopedPreferredScrollerStyle scroller_style_override(false);
 #endif
 
   ScrollView scroll_view;
+  ScrollViewTestApi test_api(&scroll_view);
   View* contents = new View;
   scroll_view.SetContents(contents);
   scroll_view.SetBoundsRect(gfx::Rect(0, 0, 100, 100));
 
   // Size the contents such that vertical scrollbar is needed.
   contents->SetBounds(0, 0, 50, 400);
   scroll_view.Layout();
-  EXPECT_EQ(100 - scroll_view.GetScrollBarWidth(), contents->parent()->width());
-  EXPECT_EQ(100, contents->parent()->height());
+  EXPECT_EQ(100 - scroll_view.GetScrollBarWidth(),
+            test_api.contents_viewport()->width());
+  EXPECT_EQ(100, test_api.contents_viewport()->height());
   CheckScrollbarVisibility(scroll_view, VERTICAL, true);
   CheckScrollbarVisibility(scroll_view, HORIZONTAL, false);
   EXPECT_TRUE(!scroll_view.horizontal_scroll_bar() ||
               !scroll_view.horizontal_scroll_bar()->visible());
   ASSERT_TRUE(scroll_view.vertical_scroll_bar() != NULL);
   EXPECT_TRUE(scroll_view.vertical_scroll_bar()->visible());
 
   // Size the contents such that horizontal scrollbar is needed.
   contents->SetBounds(0, 0, 400, 50);
   scroll_view.Layout();
-  EXPECT_EQ(100, contents->parent()->width());
+  EXPECT_EQ(100, test_api.contents_viewport()->width());
   EXPECT_EQ(100 - scroll_view.GetScrollBarHeight(),
-            contents->parent()->height());
+            test_api.contents_viewport()->height());
   CheckScrollbarVisibility(scroll_view, VERTICAL, false);
   CheckScrollbarVisibility(scroll_view, HORIZONTAL, true);
 
   // Both horizontal and vertical.
   contents->SetBounds(0, 0, 300, 400);
   scroll_view.Layout();
-  EXPECT_EQ(100 - scroll_view.GetScrollBarWidth(), contents->parent()->width());
+  EXPECT_EQ(100 - scroll_view.GetScrollBarWidth(),
+            test_api.contents_viewport()->width());
   EXPECT_EQ(100 - scroll_view.GetScrollBarHeight(),
-            contents->parent()->height());
+            test_api.contents_viewport()->height());
   CheckScrollbarVisibility(scroll_view, VERTICAL, true);
   CheckScrollbarVisibility(scroll_view, HORIZONTAL, true);
 
   // Add a border, test vertical scrollbar.
   const int kTopPadding = 1;
   const int kLeftPadding = 2;
   const int kBottomPadding = 3;
   const int kRightPadding = 4;
   scroll_view.SetBorder(Border::CreateEmptyBorder(
       kTopPadding, kLeftPadding, kBottomPadding, kRightPadding));
   contents->SetBounds(0, 0, 50, 400);
   scroll_view.Layout();
   EXPECT_EQ(
       100 - scroll_view.GetScrollBarWidth() - kLeftPadding - kRightPadding,
-      contents->parent()->width());
-  EXPECT_EQ(100 - kTopPadding - kBottomPadding, contents->parent()->height());
+      test_api.contents_viewport()->width());
+  EXPECT_EQ(100 - kTopPadding - kBottomPadding,
+            test_api.contents_viewport()->height());
   EXPECT_TRUE(!scroll_view.horizontal_scroll_bar() ||
               !scroll_view.horizontal_scroll_bar()->visible());
   ASSERT_TRUE(scroll_view.vertical_scroll_bar() != NULL);
   EXPECT_TRUE(scroll_view.vertical_scroll_bar()->visible());
   gfx::Rect bounds = scroll_view.vertical_scroll_bar()->bounds();
   EXPECT_EQ(100 - scroll_view.GetScrollBarWidth() - kRightPadding, bounds.x());
   EXPECT_EQ(100 - kRightPadding, bounds.right());
   EXPECT_EQ(kTopPadding, bounds.y());
   EXPECT_EQ(100 - kBottomPadding, bounds.bottom());
 
   // Horizontal with border.
   contents->SetBounds(0, 0, 400, 50);
   scroll_view.Layout();
-  EXPECT_EQ(100 - kLeftPadding - kRightPadding, contents->parent()->width());
+  EXPECT_EQ(100 - kLeftPadding - kRightPadding,
+            test_api.contents_viewport()->width());
   EXPECT_EQ(
       100 - scroll_view.GetScrollBarHeight() - kTopPadding - kBottomPadding,
-      contents->parent()->height());
+      test_api.contents_viewport()->height());
   ASSERT_TRUE(scroll_view.horizontal_scroll_bar() != NULL);
   EXPECT_TRUE(scroll_view.horizontal_scroll_bar()->visible());
   EXPECT_TRUE(!scroll_view.vertical_scroll_bar() ||
               !scroll_view.vertical_scroll_bar()->visible());
   bounds = scroll_view.horizontal_scroll_bar()->bounds();
   EXPECT_EQ(kLeftPadding, bounds.x());
   EXPECT_EQ(100 - kRightPadding, bounds.right());
   EXPECT_EQ(100 - kBottomPadding - scroll_view.GetScrollBarHeight(),
             bounds.y());
   EXPECT_EQ(100 - kBottomPadding, bounds.bottom());
 
   // Both horizontal and vertical with border.
   contents->SetBounds(0, 0, 300, 400);
   scroll_view.Layout();
   EXPECT_EQ(
       100 - scroll_view.GetScrollBarWidth() - kLeftPadding - kRightPadding,
-      contents->parent()->width());
+      test_api.contents_viewport()->width());
   EXPECT_EQ(
       100 - scroll_view.GetScrollBarHeight() - kTopPadding - kBottomPadding,
-      contents->parent()->height());
+      test_api.contents_viewport()->height());
   bounds = scroll_view.horizontal_scroll_bar()->bounds();
   // Check horiz.
   ASSERT_TRUE(scroll_view.horizontal_scroll_bar() != NULL);
   EXPECT_TRUE(scroll_view.horizontal_scroll_bar()->visible());
   bounds = scroll_view.horizontal_scroll_bar()->bounds();
   EXPECT_EQ(kLeftPadding, bounds.x());
   EXPECT_EQ(100 - kRightPadding - scroll_view.GetScrollBarWidth(),
             bounds.right());
   EXPECT_EQ(100 - kBottomPadding - scroll_view.GetScrollBarHeight(),
             bounds.y());
   EXPECT_EQ(100 - kBottomPadding, bounds.bottom());
   // Check vert.
   ASSERT_TRUE(scroll_view.vertical_scroll_bar() != NULL);
   EXPECT_TRUE(scroll_view.vertical_scroll_bar()->visible());
   bounds = scroll_view.vertical_scroll_bar()->bounds();
   EXPECT_EQ(100 - scroll_view.GetScrollBarWidth() - kRightPadding, bounds.x());
   EXPECT_EQ(100 - kRightPadding, bounds.right());
   EXPECT_EQ(kTopPadding, bounds.y());
   EXPECT_EQ(100 - kBottomPadding - scroll_view.GetScrollBarHeight(),
             bounds.bottom());
 }
 
 // Assertions around adding a header.
 TEST(ScrollViewTest, Header) {
   ScrollView scroll_view;
+  ScrollViewTestApi test_api(&scroll_view);
   View* contents = new View;
   CustomView* header = new CustomView;
   scroll_view.SetHeader(header);
   View* header_parent = header->parent();
   scroll_view.SetContents(contents);
   scroll_view.SetBoundsRect(gfx::Rect(0, 0, 100, 100));
   scroll_view.Layout();
   // |header|s preferred size is empty, which should result in all space going
   // to contents.
   EXPECT_EQ("0,0 100x0", header->parent()->bounds().ToString());
-  EXPECT_EQ("0,0 100x100", contents->parent()->bounds().ToString());
+  EXPECT_EQ("0,0 100x100", test_api.contents_viewport()->bounds().ToString());
 
   // Get the header a height of 20.
   header->SetPreferredSize(gfx::Size(10, 20));
   EXPECT_EQ("0,0 100x20", header->parent()->bounds().ToString());
-  EXPECT_EQ("0,20 100x80", contents->parent()->bounds().ToString());
+  EXPECT_EQ("0,20 100x80", test_api.contents_viewport()->bounds().ToString());
 
   // Remove the header.
   scroll_view.SetHeader(NULL);
   // SetHeader(NULL) deletes header.
   header = NULL;
   EXPECT_EQ("0,0 100x0", header_parent->bounds().ToString());
-  EXPECT_EQ("0,0 100x100", contents->parent()->bounds().ToString());
+  EXPECT_EQ("0,0 100x100", test_api.contents_viewport()->bounds().ToString());
 }
 
 // Verifies the scrollbars are added as necessary when a header is present.
 TEST(ScrollViewTest, ScrollBarsWithHeader) {
   ScrollView scroll_view;
+  ScrollViewTestApi test_api(&scroll_view);
   View* contents = new View;
   scroll_view.SetContents(contents);
   CustomView* header = new CustomView;
   scroll_view.SetHeader(header);
   scroll_view.SetBoundsRect(gfx::Rect(0, 0, 100, 100));
 
   header->SetPreferredSize(gfx::Size(10, 20));
 
   // Size the contents such that vertical scrollbar is needed.
   contents->SetBounds(0, 0, 50, 400);
   scroll_view.Layout();
-  EXPECT_EQ(0, contents->parent()->x());
-  EXPECT_EQ(20, contents->parent()->y());
-  EXPECT_EQ(100 - scroll_view.GetScrollBarWidth(), contents->parent()->width());
-  EXPECT_EQ(80, contents->parent()->height());
+  EXPECT_EQ(0, test_api.contents_viewport()->x());
+  EXPECT_EQ(20, test_api.contents_viewport()->y());
+  EXPECT_EQ(100 - scroll_view.GetScrollBarWidth(),
+            test_api.contents_viewport()->width());
+  EXPECT_EQ(80, test_api.contents_viewport()->height());
   EXPECT_EQ(0, header->parent()->x());
   EXPECT_EQ(0, header->parent()->y());
   EXPECT_EQ(100 - scroll_view.GetScrollBarWidth(), header->parent()->width());
   EXPECT_EQ(20, header->parent()->height());
   EXPECT_TRUE(!scroll_view.horizontal_scroll_bar() ||
               !scroll_view.horizontal_scroll_bar()->visible());
   ASSERT_TRUE(scroll_view.vertical_scroll_bar() != NULL);
   EXPECT_TRUE(scroll_view.vertical_scroll_bar()->visible());
   // Make sure the vertical scrollbar overlaps the header.
   EXPECT_EQ(header->y(), scroll_view.vertical_scroll_bar()->y());
   EXPECT_EQ(header->y(), contents->y());
 
   // Size the contents such that horizontal scrollbar is needed.
   contents->SetBounds(0, 0, 400, 50);
   scroll_view.Layout();
-  EXPECT_EQ(0, contents->parent()->x());
-  EXPECT_EQ(20, contents->parent()->y());
-  EXPECT_EQ(100, contents->parent()->width());
+  EXPECT_EQ(0, test_api.contents_viewport()->x());
+  EXPECT_EQ(20, test_api.contents_viewport()->y());
+  EXPECT_EQ(100, test_api.contents_viewport()->width());
   EXPECT_EQ(100 - scroll_view.GetScrollBarHeight() - 20,
-            contents->parent()->height());
+            test_api.contents_viewport()->height());
   EXPECT_EQ(0, header->parent()->x());
   EXPECT_EQ(0, header->parent()->y());
   EXPECT_EQ(100, header->parent()->width());
   EXPECT_EQ(20, header->parent()->height());
   ASSERT_TRUE(scroll_view.horizontal_scroll_bar() != NULL);
   EXPECT_TRUE(scroll_view.horizontal_scroll_bar()->visible());
   EXPECT_TRUE(!scroll_view.vertical_scroll_bar() ||
               !scroll_view.vertical_scroll_bar()->visible());
 
   // Both horizontal and vertical.
   contents->SetBounds(0, 0, 300, 400);
   scroll_view.Layout();
-  EXPECT_EQ(0, contents->parent()->x());
-  EXPECT_EQ(20, contents->parent()->y());
-  EXPECT_EQ(100 - scroll_view.GetScrollBarWidth(), contents->parent()->width());
+  EXPECT_EQ(0, test_api.contents_viewport()->x());
+  EXPECT_EQ(20, test_api.contents_viewport()->y());
+  EXPECT_EQ(100 - scroll_view.GetScrollBarWidth(),
+            test_api.contents_viewport()->width());
   EXPECT_EQ(100 - scroll_view.GetScrollBarHeight() - 20,
-            contents->parent()->height());
+            test_api.contents_viewport()->height());
   EXPECT_EQ(0, header->parent()->x());
   EXPECT_EQ(0, header->parent()->y());
   EXPECT_EQ(100 - scroll_view.GetScrollBarWidth(), header->parent()->width());
   EXPECT_EQ(20, header->parent()->height());
   ASSERT_TRUE(scroll_view.horizontal_scroll_bar() != NULL);
   EXPECT_TRUE(scroll_view.horizontal_scroll_bar()->visible());
   ASSERT_TRUE(scroll_view.vertical_scroll_bar() != NULL);
   EXPECT_TRUE(scroll_view.vertical_scroll_bar()->visible());
 }
 
 // Verifies the header scrolls horizontally with the content.
 TEST(ScrollViewTest, HeaderScrollsWithContent) {
   ScrollView scroll_view;
+  ScrollViewTestApi test_api(&scroll_view);
   CustomView* contents = new CustomView;
   scroll_view.SetContents(contents);
   contents->SetPreferredSize(gfx::Size(500, 500));
 
   CustomView* header = new CustomView;
   scroll_view.SetHeader(header);
   header->SetPreferredSize(gfx::Size(500, 20));
 
   scroll_view.SetBoundsRect(gfx::Rect(0, 0, 100, 100));
-  EXPECT_EQ("0,0", contents->bounds().origin().ToString());
+  EXPECT_EQ("0,0", test_api.IntegralViewOffset().ToString());
   EXPECT_EQ("0,0", header->bounds().origin().ToString());
 
   // Scroll the horizontal scrollbar.
   ASSERT_TRUE(scroll_view.horizontal_scroll_bar());
   scroll_view.ScrollToPosition(
       const_cast<ScrollBar*>(scroll_view.horizontal_scroll_bar()), 1);
-  EXPECT_EQ("-1,0", contents->bounds().origin().ToString());
+  EXPECT_EQ("-1,0", test_api.IntegralViewOffset().ToString());
   EXPECT_EQ("-1,0", header->bounds().origin().ToString());
 
   // Scrolling the vertical scrollbar shouldn't effect the header.
   ASSERT_TRUE(scroll_view.vertical_scroll_bar());
   scroll_view.ScrollToPosition(
       const_cast<ScrollBar*>(scroll_view.vertical_scroll_bar()), 1);
-  EXPECT_EQ("-1,-1", contents->bounds().origin().ToString());
+  EXPECT_EQ("-1,-1", test_api.IntegralViewOffset().ToString());
   EXPECT_EQ("-1,0", header->bounds().origin().ToString());
 }
 
 // Verifies ScrollRectToVisible() on the child works.
 TEST(ScrollViewTest, ScrollRectToVisible) {
+#if defined(OS_MACOSX)
+  ui::test::ScopedPreferredScrollerStyle scroller_style_override(false);
+#endif
   ScrollView scroll_view;
+  ScrollViewTestApi test_api(&scroll_view);
   CustomView* contents = new CustomView;
   scroll_view.SetContents(contents);
   contents->SetPreferredSize(gfx::Size(500, 1000));
 
   scroll_view.SetBoundsRect(gfx::Rect(0, 0, 100, 100));
   scroll_view.Layout();
-  EXPECT_EQ("0,0", contents->bounds().origin().ToString());
+  EXPECT_EQ("0,0", test_api.IntegralViewOffset().ToString());
 
   // Scroll to y=405 height=10, this should make the y position of the content
   // at (405 + 10) - viewport_height (scroll region bottom aligned).
   contents->ScrollRectToVisible(gfx::Rect(0, 405, 10, 10));
-  const int viewport_height = contents->parent()->height();
-  EXPECT_EQ(-(415 - viewport_height), contents->y());
+  const int viewport_height = test_api.contents_viewport()->height();
+
+  // Expect there to be a horizontal scrollbar, making the viewport shorter.
+  EXPECT_LT(viewport_height, 100);
+
+  gfx::ScrollOffset offset = test_api.CurrentOffset();
+  EXPECT_EQ(415 - viewport_height, offset.y());
 
   // Scroll to the current y-location and 10x10; should do nothing.
-  contents->ScrollRectToVisible(gfx::Rect(0, -contents->y(), 10, 10));
-  EXPECT_EQ(-(415 - viewport_height), contents->y());
+  contents->ScrollRectToVisible(gfx::Rect(0, offset.y(), 10, 10));
+  EXPECT_EQ(415 - viewport_height, test_api.CurrentOffset().y());
 }
 
 // Verifies ClipHeightTo() uses the height of the content when it is between the
 // minimum and maximum height values.
 TEST(ScrollViewTest, ClipHeightToNormalContentHeight) {
   ScrollView scroll_view;
 
   scroll_view.ClipHeightTo(kMinHeight, kMaxHeight);
 
   const int kNormalContentHeight = 75;
@@ skipping 80 matching lines @@
   EXPECT_EQ(scroll_view.contents()->size().width(), expected_width);
   EXPECT_EQ(scroll_view.contents()->size().height(), 1000 * expected_width);
   EXPECT_EQ(gfx::Size(kWidth, kMaxHeight), scroll_view.size());
 }
 
 TEST(ScrollViewTest, CornerViewVisibility) {
   ScrollView scroll_view;
   View* contents = new View;
   scroll_view.SetContents(contents);
   scroll_view.SetBoundsRect(gfx::Rect(0, 0, 100, 100));
-  View* corner_view = scroll_view.corner_view_;
+  View* corner_view = ScrollViewTestApi(&scroll_view).corner_view();
 
   // Corner view should be visible when both scrollbars are visible.
   contents->SetBounds(0, 0, 200, 200);
   scroll_view.Layout();
   EXPECT_EQ(&scroll_view, corner_view->parent());
   EXPECT_TRUE(corner_view->visible());
 
   // Corner view should be aligned to the scrollbars.
   EXPECT_EQ(scroll_view.vertical_scroll_bar()->x(), corner_view->x());
   EXPECT_EQ(scroll_view.horizontal_scroll_bar()->y(), corner_view->y());
@@ skipping 24 matching lines @@
 
 #if defined(OS_MACOSX)
 // Tests the overlay scrollbars on Mac. Ensure that they show up properly and
 // do not overlap each other.
 TEST(ScrollViewTest, CocoaOverlayScrollBars) {
   std::unique_ptr<ui::test::ScopedPreferredScrollerStyle>
       scroller_style_override;
   scroller_style_override.reset(
       new ui::test::ScopedPreferredScrollerStyle(true));
   ScrollView scroll_view;
+  ScrollViewTestApi test_api(&scroll_view);
   View* contents = new View;
   scroll_view.SetContents(contents);
   scroll_view.SetBoundsRect(gfx::Rect(0, 0, 100, 100));
 
   // Size the contents such that vertical scrollbar is needed.
   // Since it is overlaid, the ViewPort size should match the ScrollView.
   contents->SetBounds(0, 0, 50, 400);
   scroll_view.Layout();
-  EXPECT_EQ(100, contents->parent()->width());
-  EXPECT_EQ(100, contents->parent()->height());
+  EXPECT_EQ(100, test_api.contents_viewport()->width());
+  EXPECT_EQ(100, test_api.contents_viewport()->height());
   EXPECT_EQ(0, scroll_view.GetScrollBarWidth());
   CheckScrollbarVisibility(scroll_view, VERTICAL, true);
   CheckScrollbarVisibility(scroll_view, HORIZONTAL, false);
 
   // Size the contents such that horizontal scrollbar is needed.
   contents->SetBounds(0, 0, 400, 50);
   scroll_view.Layout();
-  EXPECT_EQ(100, contents->parent()->width());
-  EXPECT_EQ(100, contents->parent()->height());
+  EXPECT_EQ(100, test_api.contents_viewport()->width());
+  EXPECT_EQ(100, test_api.contents_viewport()->height());
   EXPECT_EQ(0, scroll_view.GetScrollBarHeight());
   CheckScrollbarVisibility(scroll_view, VERTICAL, false);
   CheckScrollbarVisibility(scroll_view, HORIZONTAL, true);
 
   // Both horizontal and vertical scrollbars.
   contents->SetBounds(0, 0, 300, 400);
   scroll_view.Layout();
-  EXPECT_EQ(100, contents->parent()->width());
-  EXPECT_EQ(100, contents->parent()->height());
+  EXPECT_EQ(100, test_api.contents_viewport()->width());
+  EXPECT_EQ(100, test_api.contents_viewport()->height());
   EXPECT_EQ(0, scroll_view.GetScrollBarWidth());
   EXPECT_EQ(0, scroll_view.GetScrollBarHeight());
   CheckScrollbarVisibility(scroll_view, VERTICAL, true);
   CheckScrollbarVisibility(scroll_view, HORIZONTAL, true);
 
   // Make sure the horizontal and vertical scrollbars don't overlap each other.
   gfx::Rect vert_bounds = scroll_view.vertical_scroll_bar()->bounds();
   gfx::Rect horiz_bounds = scroll_view.horizontal_scroll_bar()->bounds();
   EXPECT_EQ(vert_bounds.x(), horiz_bounds.right());
   EXPECT_EQ(horiz_bounds.y(), vert_bounds.bottom());
 
   // Switch to the non-overlay style and check that the ViewPort is now sized
   // to be smaller, and ScrollbarWidth and ScrollbarHeight are non-zero.
   scroller_style_override.reset(
       new ui::test::ScopedPreferredScrollerStyle(false));
-  EXPECT_EQ(100 - scroll_view.GetScrollBarWidth(), contents->parent()->width());
+  EXPECT_EQ(100 - scroll_view.GetScrollBarWidth(),
+            test_api.contents_viewport()->width());
   EXPECT_EQ(100 - scroll_view.GetScrollBarHeight(),
-            contents->parent()->height());
+            test_api.contents_viewport()->height());
   EXPECT_NE(0, scroll_view.GetScrollBarWidth());
   EXPECT_NE(0, scroll_view.GetScrollBarHeight());
 }
 #endif
 
+// Test scrolling behavior when clicking on the scroll track.
+TEST_F(WidgetScrollViewTest, ScrollTrackScrolling) {
+  // Set up with a vertical scroller.
+  ScrollView* scroll_view =
+      AddScrollViewWithContentSize(gfx::Size(10, kDefaultHeight * 5));
+  ScrollViewTestApi test_api(scroll_view);
+  BaseScrollBar* scroll_bar = test_api.GetBaseScrollBar(VERTICAL);
+  View* thumb = test_api.GetScrollBarThumb(VERTICAL);
+
+  // Click in the middle of the track, ensuring it's below the thumb.
+  const gfx::Point location = scroll_bar->bounds().CenterPoint();
+  EXPECT_GT(location.y(), thumb->bounds().bottom());
+  ui::MouseEvent press(TestLeftMouseAt(location, ui::ET_MOUSE_PRESSED));
+  ui::MouseEvent release(TestLeftMouseAt(location, ui::ET_MOUSE_RELEASED));
+
+  const base::Timer& timer = test_api.GetScrollBarTimer(VERTICAL);
+  EXPECT_FALSE(timer.IsRunning());
+
+  EXPECT_EQ(0, scroll_view->GetVisibleRect().y());
+  scroll_bar->OnMouseEvent(&press);
+
+  // Clicking the scroll track should scroll one "page".
+  EXPECT_EQ(kDefaultHeight, scroll_view->GetVisibleRect().y());
+
+  // While the mouse is pressed, timer should trigger more scroll events.
+  EXPECT_TRUE(timer.IsRunning());
+
+  // Upon release timer should stop (and scroll position should remain).
+  scroll_bar->OnMouseEvent(&release);
+  EXPECT_FALSE(timer.IsRunning());
+  EXPECT_EQ(kDefaultHeight, scroll_view->GetVisibleRect().y());
+}
+
 }  // namespace views