Mac: Don't repaint scrollbars every frame

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 13487d835d657377cc8cd2af7d229436487fdd1a..cf8ac98314345e874390090476e00ed25b6dd1d3 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollableAreaTest.cpp
+++ b/third_party/WebKit/Source/platform/scroll/ScrollableAreaTest.cpp
@@ -5,6 +5,8 @@
 #include "config.h"
 #include "platform/scroll/ScrollableArea.h"
 
+#include "platform/scroll/ScrollbarTheme.h"
+#include "platform/scroll/ScrollbarThemeMock.h"
 #include "platform/testing/TestingPlatformSupport.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebScheduler.h"
@@ -127,4 +129,36 @@ TEST_F(ScrollableAreaTest, ScrollAnimatorCurrentPositionShouldBeSync)
     EXPECT_EQ(100.0, scrollableArea->scrollAnimator()->currentPosition().y());
 }
 
+TEST_F(ScrollableAreaTest, ScrollbarTrackAndThumbRepaint)
+{
+    ScrollbarTheme::setMockScrollbarsEnabled(true);
+    ScrollbarThemeMock::setShouldRepaintAllPartsOnInvalidation(true);
+
+    OwnPtrWillBeRawPtr<MockScrollableArea> scrollableArea = MockScrollableArea::create(IntPoint(0, 100));
+    RefPtrWillBeRawPtr<Scrollbar> scrollbar = Scrollbar::create(scrollableArea.get(), HorizontalScrollbar, RegularScrollbar);
+
+    EXPECT_TRUE(scrollbar->trackBackgroudNeedsRepaint());
+    EXPECT_TRUE(scrollbar->thumbNeedsRepaint());
+    scrollbar->setNeedsPaintInvalidation();
+    EXPECT_TRUE(scrollbar->trackBackgroudNeedsRepaint());
+    EXPECT_TRUE(scrollbar->thumbNeedsRepaint());
+
+    scrollbar->setTrackBackgroudNeedsRepaint(false);
+    scrollbar->setThumbNeedsRepaint(false);
+    EXPECT_FALSE(scrollbar->trackBackgroudNeedsRepaint());
+    EXPECT_FALSE(scrollbar->thumbNeedsRepaint());
+    scrollbar->setNeedsPaintInvalidation();
+    EXPECT_TRUE(scrollbar->trackBackgroudNeedsRepaint());
+    EXPECT_TRUE(scrollbar->thumbNeedsRepaint());
+
+    ScrollbarThemeMock::setShouldRepaintAllPartsOnInvalidation(false);
+    scrollbar->setTrackBackgroudNeedsRepaint(false);
+    scrollbar->setThumbNeedsRepaint(false);
+    EXPECT_FALSE(scrollbar->trackBackgroudNeedsRepaint());
+    EXPECT_FALSE(scrollbar->thumbNeedsRepaint());
+    scrollbar->setNeedsPaintInvalidation();
+    EXPECT_FALSE(scrollbar->trackBackgroudNeedsRepaint());
+    EXPECT_FALSE(scrollbar->thumbNeedsRepaint());
+}
+
 } // namespace blink