MacViews: Fix scrolling when clicking on the views::ScrollView scroll track

ui/views/controls/scroll_view_unittest.cc

Index: ui/views/controls/scroll_view_unittest.cc
diff --git a/ui/views/controls/scroll_view_unittest.cc b/ui/views/controls/scroll_view_unittest.cc
index d90784ca906d5d57097fece67c4518275f0ea19c..38238f3a5562b4320a580337dbe662eff672fe8a 100644
--- a/ui/views/controls/scroll_view_unittest.cc
+++ b/ui/views/controls/scroll_view_unittest.cc
@@ -7,14 +7,54 @@
 #include "base/macros.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*>(

[sky, 2016/08/01 22:33:35]

ick!

[tapted, 2016/08/02 00:05:08]

yeah.. that was an interesting journey. I guess this is http://crbug.com/93103
"Get rid of NativeScrollBar", which I think is still valid. Mac seems to be
happy with the flattened class structure, so I should be able to explore this
for other platforms soon..

+          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_;
+  }
+
+  View* corner_view() { return scroll_view_->corner_view_; }
+
+ private:
+  ScrollView* scroll_view_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScrollViewTestApi);
+};
+
+}  // namespace test
 
 namespace {
 
@@ -22,8 +62,6 @@ 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:
@@ -67,8 +105,63 @@ void CheckScrollbarVisibility(const ScrollView& scroll_view,
   }
 }
 
+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;

[sky, 2016/08/01 22:33:35]

static on these two?

[tapted, 2016/08/02 00:05:08]

Done.

I'd actually flip-flopped on this a bit. When they are static, they also need a
separate definition, which didn't feel as neat. I think passing them directly to
the EXPECT macros (i.e. not part of an expression) results in the compiler
generating code that wants an address for the constant. `constexpr` didn't
change this. An enum constant would avoid it, but it also felt less neat. Enum
constants haven't really caught on in chrome, but would probably be my choice in
isolation.

Anyway, went with static :)

+  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();
+    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;
@@ -436,7 +529,7 @@ TEST(ScrollViewTest, CornerViewVisibility) {
   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);
@@ -532,4 +625,37 @@ TEST(ScrollViewTest, CocoaOverlayScrollBars) {
 }
 #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