Oilpan: make ScrollableAreaTest.ScrollbarTrackAndThumbRepaint work.

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

 // Copyright 2015 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 "config.h"
 #include "platform/scroll/ScrollableArea.h"
 
 #include "platform/graphics/GraphicsLayer.h"
 #include "platform/scroll/ScrollbarTheme.h"
 #include "platform/scroll/ScrollbarThemeMock.h"
@@ skipping 158 matching lines @@
     EXPECT_TRUE(scrollbar->thumbNeedsRepaint());
 
     EXPECT_CALL(theme, shouldRepaintAllPartsOnInvalidation()).WillRepeatedly(Return(false));
     scrollbar->setTrackNeedsRepaint(false);
     scrollbar->setThumbNeedsRepaint(false);
     EXPECT_FALSE(scrollbar->trackNeedsRepaint());
     EXPECT_FALSE(scrollbar->thumbNeedsRepaint());
     scrollbar->setNeedsPaintInvalidation();
     EXPECT_FALSE(scrollbar->trackNeedsRepaint());
     EXPECT_FALSE(scrollbar->thumbNeedsRepaint());
+
+    // Forced GC in order to finalize objects depending on the mock object.
+    Heap::collectAllGarbage();

[jbroman, 2015/12/16 12:18:12]

The object in question still has a RawPtr<Scrollbar> in scope; is this
guaranteed to work?

[sof, 2015/12/16 12:20:38]

The GCs performed by this are precise (non-conservative), so none of the objects
created in this test will be reachable. => they'll be swept out, as wanted.

 }
 
 class MockGraphicsLayerClient : public GraphicsLayerClient {
 public:
     IntRect computeInterestRect(const GraphicsLayer*, const IntRect&) const { return IntRect(); }
     void paintContents(const GraphicsLayer*, GraphicsContext&, GraphicsLayerPaintingPhase, const IntRect&) const override { }
     String debugName(const GraphicsLayer*) const override { return String(); }
     bool isTrackingPaintInvalidations() const override { return true; }
 };
 
@@ skipping 13 matching lines @@
 
     EXPECT_CALL(*scrollableArea, layerForHorizontalScrollbar()).WillRepeatedly(Return(&graphicsLayer));
 
     RefPtrWillBeRawPtr<Scrollbar> scrollbar = Scrollbar::create(scrollableArea.get(), HorizontalScrollbar, RegularScrollbar);
     graphicsLayer.resetTrackedPaintInvalidations();
     scrollbar->setNeedsPaintInvalidation();
     EXPECT_TRUE(graphicsLayer.hasTrackedPaintInvalidations());
 }
 
 } // namespace blink