Move ScrollableArea timer to TaskRunnerTimer.

third_party/WebKit/Source/core/frame/RootFrameViewportTest.cpp

Index: third_party/WebKit/Source/core/frame/RootFrameViewportTest.cpp
diff --git a/third_party/WebKit/Source/core/frame/RootFrameViewportTest.cpp b/third_party/WebKit/Source/core/frame/RootFrameViewportTest.cpp
index cc910549212011fb8c16d4916f403e80a23c6a8a..4249201b758b1ad53db73be9eae00bb5ab8c66cd 100644
--- a/third_party/WebKit/Source/core/frame/RootFrameViewportTest.cpp
+++ b/third_party/WebKit/Source/core/frame/RootFrameViewportTest.cpp
@@ -8,6 +8,9 @@
 #include "platform/geometry/DoubleRect.h"
 #include "platform/geometry/LayoutRect.h"
 #include "platform/scroll/ScrollableArea.h"
+#include "public/platform/Platform.h"
+#include "public/platform/WebScheduler.h"
+#include "public/platform/WebThread.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 #define EXPECT_POINT_EQ(expected, actual)    \
@@ -68,6 +71,10 @@ class ScrollableAreaStub : public GarbageCollectedFinalized<ScrollableAreaStub>,
     m_contentsSize = contentsSize;
   }
 
+  RefPtr<WebTaskRunner> getTimerTaskRunner() const final {
+    return Platform::current()->currentThread()->scheduler()->timerTaskRunner();
+  }
+
   DEFINE_INLINE_VIRTUAL_TRACE() { ScrollableArea::trace(visitor); }
 
  protected: