Reland: Make ScrollbarThemeAura selectively invalidate scrollbar parts.

third_party/WebKit/Source/platform/scroll/ScrollableAreaTest.cpp

Index: third_party/WebKit/Source/platform/scroll/ScrollableAreaTest.cpp
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollableAreaTest.cpp b/third_party/WebKit/Source/platform/scroll/ScrollableAreaTest.cpp
index 8f4b977c9200c3206e84f955a3d162b784f50cb3..8f2531784033cdf351179ffb67801f9164ab0388 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollableAreaTest.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollableAreaTest.cpp
@@ -18,6 +18,7 @@ namespace blink {
 
 namespace {
 
+using testing::_;
 using testing::Return;
 
 class MockScrollableArea : public NoBaseWillBeGarbageCollectedFinalized<MockScrollableArea>, public ScrollableArea {
@@ -32,12 +33,15 @@ public:
     MOCK_CONST_METHOD1(scrollSize, int(ScrollbarOrientation));
     MOCK_CONST_METHOD0(isScrollCornerVisible, bool());
     MOCK_CONST_METHOD0(scrollCornerRect, IntRect());
+    MOCK_CONST_METHOD0(horizontalScrollbar, Scrollbar*());
+    MOCK_CONST_METHOD0(verticalScrollbar, Scrollbar*());
     MOCK_METHOD0(scrollControlWasSetNeedsPaintInvalidation, void());
     MOCK_CONST_METHOD0(enclosingScrollableArea, ScrollableArea*());
     MOCK_CONST_METHOD1(visibleContentRect, IntRect(IncludeScrollbarsInRect));
     MOCK_CONST_METHOD0(contentsSize, IntSize());
     MOCK_CONST_METHOD0(scrollableAreaBoundingBox, IntRect());
     MOCK_CONST_METHOD0(layerForHorizontalScrollbar, GraphicsLayer*());
+    MOCK_CONST_METHOD0(layerForVerticalScrollbar, GraphicsLayer*());
 
     bool userInputScrollable(ScrollbarOrientation) const override { return true; }
     bool scrollbarsCanBeActive () const override { return true; }
@@ -51,6 +55,10 @@ public:
     bool scrollAnimatorEnabled() const override { return false; }
     int pageStep(ScrollbarOrientation) const override { return 0; }
 
+    using ScrollableArea::horizontalScrollbarNeedsPaintInvalidation;
+    using ScrollableArea::verticalScrollbarNeedsPaintInvalidation;
+    using ScrollableArea::clearNeedsPaintInvalidationForScrollControls;
+
     DEFINE_INLINE_VIRTUAL_TRACE()
     {
         ScrollableArea::trace(visitor);
@@ -142,6 +150,7 @@ namespace {
 class ScrollbarThemeWithMockInvalidation : public ScrollbarThemeMock {
 public:
     MOCK_CONST_METHOD0(shouldRepaintAllPartsOnInvalidation, bool());
+    MOCK_CONST_METHOD3(invalidateOnThumbPositionChange, ScrollbarPart(const ScrollbarThemeClient&, float, float));
 };
 
 } // namespace
@@ -163,18 +172,20 @@ TEST_F(ScrollableAreaTest, ScrollbarTrackAndThumbRepaint)
     scrollbar->setThumbNeedsRepaint(false);
     EXPECT_FALSE(scrollbar->trackNeedsRepaint());
     EXPECT_FALSE(scrollbar->thumbNeedsRepaint());
-    scrollbar->setNeedsPaintInvalidation();
+    scrollbar->setNeedsPaintInvalidation(ThumbPart);
     EXPECT_TRUE(scrollbar->trackNeedsRepaint());
     EXPECT_TRUE(scrollbar->thumbNeedsRepaint());
 
+    // When not all parts are repainted on invalidation,
+    // setNeedsPaintInvalidation sets repaint bits only on the requested parts.
     EXPECT_CALL(theme, shouldRepaintAllPartsOnInvalidation()).WillRepeatedly(Return(false));
     scrollbar->setTrackNeedsRepaint(false);
     scrollbar->setThumbNeedsRepaint(false);
     EXPECT_FALSE(scrollbar->trackNeedsRepaint());
     EXPECT_FALSE(scrollbar->thumbNeedsRepaint());
-    scrollbar->setNeedsPaintInvalidation();
+    scrollbar->setNeedsPaintInvalidation(ThumbPart);
     EXPECT_FALSE(scrollbar->trackNeedsRepaint());
-    EXPECT_FALSE(scrollbar->thumbNeedsRepaint());
+    EXPECT_TRUE(scrollbar->thumbNeedsRepaint());
 
     // Forced GC in order to finalize objects depending on the mock object.
     Heap::collectAllGarbage();
@@ -210,4 +221,101 @@ TEST_F(ScrollableAreaTest, ScrollbarGraphicsLayerInvalidation)
     EXPECT_TRUE(graphicsLayer.hasTrackedPaintInvalidations());
 }
 
+TEST_F(ScrollableAreaTest, InvalidatesNonCompositedScrollbarsWhenThumbMoves)
+{
+    ScrollbarThemeWithMockInvalidation theme;
+    OwnPtrWillBeRawPtr<MockScrollableArea> scrollableArea = MockScrollableArea::create(IntPoint(100, 100));
+    RefPtrWillBeRawPtr<Scrollbar> horizontalScrollbar = Scrollbar::createForTesting(scrollableArea.get(), HorizontalScrollbar, RegularScrollbar, &theme);
+    RefPtrWillBeRawPtr<Scrollbar> verticalScrollbar = Scrollbar::createForTesting(scrollableArea.get(), VerticalScrollbar, RegularScrollbar, &theme);
+    EXPECT_CALL(*scrollableArea, horizontalScrollbar()).WillRepeatedly(Return(horizontalScrollbar.get()));
+    EXPECT_CALL(*scrollableArea, verticalScrollbar()).WillRepeatedly(Return(verticalScrollbar.get()));
+
+    // Regardless of whether the theme invalidates any parts, non-composited
+    // scrollbars have to be repainted if the thumb moves.
+    EXPECT_CALL(*scrollableArea, layerForHorizontalScrollbar()).WillRepeatedly(Return(nullptr));
+    EXPECT_CALL(*scrollableArea, layerForVerticalScrollbar()).WillRepeatedly(Return(nullptr));
+    ASSERT_FALSE(scrollableArea->hasLayerForVerticalScrollbar());
+    ASSERT_FALSE(scrollableArea->hasLayerForHorizontalScrollbar());
+    EXPECT_CALL(theme, shouldRepaintAllPartsOnInvalidation()).WillRepeatedly(Return(false));
+    EXPECT_CALL(theme, invalidateOnThumbPositionChange(_, _, _)).WillRepeatedly(Return(NoPart));
+
+    // A scroll in each direction should only invalidate one scrollbar.
+    scrollableArea->setScrollPosition(DoublePoint(0, 50), ProgrammaticScroll);
+    EXPECT_FALSE(scrollableArea->horizontalScrollbarNeedsPaintInvalidation());
+    EXPECT_TRUE(scrollableArea->verticalScrollbarNeedsPaintInvalidation());
+    scrollableArea->clearNeedsPaintInvalidationForScrollControls();
+    scrollableArea->setScrollPosition(DoublePoint(50, 50), ProgrammaticScroll);
+    EXPECT_TRUE(scrollableArea->horizontalScrollbarNeedsPaintInvalidation());
+    EXPECT_FALSE(scrollableArea->verticalScrollbarNeedsPaintInvalidation());
+    scrollableArea->clearNeedsPaintInvalidationForScrollControls();
+
+    // Forced GC in order to finalize objects depending on the mock object.
+    Heap::collectAllGarbage();
+}
+
+
+TEST_F(ScrollableAreaTest, InvalidatesCompositedScrollbarsIfPartsNeedRepaint)
+{
+    ScrollbarThemeWithMockInvalidation theme;
+    OwnPtrWillBeRawPtr<MockScrollableArea> scrollableArea = MockScrollableArea::create(IntPoint(100, 100));
+    RefPtrWillBeRawPtr<Scrollbar> horizontalScrollbar = Scrollbar::createForTesting(scrollableArea.get(), HorizontalScrollbar, RegularScrollbar, &theme);
+    horizontalScrollbar->setTrackNeedsRepaint(false);
+    horizontalScrollbar->setThumbNeedsRepaint(false);
+    RefPtrWillBeRawPtr<Scrollbar> verticalScrollbar = Scrollbar::createForTesting(scrollableArea.get(), VerticalScrollbar, RegularScrollbar, &theme);
+    verticalScrollbar->setTrackNeedsRepaint(false);
+    verticalScrollbar->setThumbNeedsRepaint(false);
+    EXPECT_CALL(*scrollableArea, horizontalScrollbar()).WillRepeatedly(Return(horizontalScrollbar.get()));
+    EXPECT_CALL(*scrollableArea, verticalScrollbar()).WillRepeatedly(Return(verticalScrollbar.get()));
+
+    // Composited scrollbars only need repainting when parts become invalid
+    // (e.g. if the track changes appearance when the thumb reaches the end).
+    MockGraphicsLayerClient graphicsLayerClient;
+    MockGraphicsLayer layerForHorizontalScrollbar(&graphicsLayerClient);
+    layerForHorizontalScrollbar.setDrawsContent(true);
+    layerForHorizontalScrollbar.setSize(FloatSize(10, 10));
+    MockGraphicsLayer layerForVerticalScrollbar(&graphicsLayerClient);
+    layerForVerticalScrollbar.setDrawsContent(true);
+    layerForVerticalScrollbar.setSize(FloatSize(10, 10));
+    EXPECT_CALL(*scrollableArea, layerForHorizontalScrollbar()).WillRepeatedly(Return(&layerForHorizontalScrollbar));
+    EXPECT_CALL(*scrollableArea, layerForVerticalScrollbar()).WillRepeatedly(Return(&layerForVerticalScrollbar));
+    ASSERT_TRUE(scrollableArea->hasLayerForHorizontalScrollbar());
+    ASSERT_TRUE(scrollableArea->hasLayerForVerticalScrollbar());
+    EXPECT_CALL(theme, shouldRepaintAllPartsOnInvalidation()).WillRepeatedly(Return(false));
+
+    // First, we'll scroll horizontally, and the theme will require repainting
+    // the back button (i.e. the track).
+    EXPECT_CALL(theme, invalidateOnThumbPositionChange(_, _, _)).WillOnce(Return(BackButtonStartPart));
+    scrollableArea->setScrollPosition(DoublePoint(50, 0), ProgrammaticScroll);
+    EXPECT_TRUE(layerForHorizontalScrollbar.hasTrackedPaintInvalidations());
+    EXPECT_FALSE(layerForVerticalScrollbar.hasTrackedPaintInvalidations());
+    EXPECT_TRUE(horizontalScrollbar->trackNeedsRepaint());
+    EXPECT_FALSE(horizontalScrollbar->thumbNeedsRepaint());
+    layerForHorizontalScrollbar.resetTrackedPaintInvalidations();
+    horizontalScrollbar->setTrackNeedsRepaint(false);
+
+    // Next, we'll scroll vertically, but invalidate the thumb.
+    EXPECT_CALL(theme, invalidateOnThumbPositionChange(_, _, _)).WillOnce(Return(ThumbPart));
+    scrollableArea->setScrollPosition(DoublePoint(50, 50), ProgrammaticScroll);
+    EXPECT_FALSE(layerForHorizontalScrollbar.hasTrackedPaintInvalidations());
+    EXPECT_TRUE(layerForVerticalScrollbar.hasTrackedPaintInvalidations());
+    EXPECT_FALSE(verticalScrollbar->trackNeedsRepaint());
+    EXPECT_TRUE(verticalScrollbar->thumbNeedsRepaint());
+    layerForVerticalScrollbar.resetTrackedPaintInvalidations();
+    verticalScrollbar->setThumbNeedsRepaint(false);
+
+    // Next we'll scroll in both, but the thumb position moving requires no
+    // invalidations.
+    EXPECT_CALL(theme, invalidateOnThumbPositionChange(_, _, _)).Times(2).WillRepeatedly(Return(NoPart));
+    scrollableArea->setScrollPosition(DoublePoint(70, 70), ProgrammaticScroll);
+    EXPECT_FALSE(layerForHorizontalScrollbar.hasTrackedPaintInvalidations());
+    EXPECT_FALSE(layerForVerticalScrollbar.hasTrackedPaintInvalidations());
+    EXPECT_FALSE(horizontalScrollbar->trackNeedsRepaint());
+    EXPECT_FALSE(horizontalScrollbar->thumbNeedsRepaint());
+    EXPECT_FALSE(verticalScrollbar->trackNeedsRepaint());
+    EXPECT_FALSE(verticalScrollbar->thumbNeedsRepaint());
+
+    // Forced GC in order to finalize objects depending on the mock object.
+    Heap::collectAllGarbage();
+}
+
 } // namespace blink