Refactor TimeBase to post tasks. Workers to use real Idle tasks.

Source/platform/scroll/ScrollableAreaTest.cpp

Index: Source/platform/scroll/ScrollableAreaTest.cpp
diff --git a/Source/platform/scroll/ScrollableAreaTest.cpp b/Source/platform/scroll/ScrollableAreaTest.cpp
index a435664b5411f4ba1beeb51afc39be2e9548c9c4..0d6426fc095ffdcd74403348aa00ce041e138c0d 100644
--- a/Source/platform/scroll/ScrollableAreaTest.cpp
+++ b/Source/platform/scroll/ScrollableAreaTest.cpp
@@ -6,6 +6,9 @@
 
 #include "platform/scroll/ScrollableArea.h"
 
+#include "public/platform/Platform.h"
+#include "public/platform/WebScheduler.h"
+#include "public/platform/WebThread.h"
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
@@ -47,11 +50,86 @@ private:
     IntPoint m_maximumScrollPosition;
 };
 
+class FakeWebThread : public WebThread {
+public:
+    FakeWebThread() { }
+    ~FakeWebThread() override { }
+
+    void postTask(const WebTraceLocation&, Task*)
+    {
+        ASSERT_NOT_REACHED();
+    }
+
+    virtual void postDelayedTask(const WebTraceLocation&, Task*, long long)
+    {
+        ASSERT_NOT_REACHED();
+    }
+
+    virtual bool isCurrentThread() const
+    {
+        ASSERT_NOT_REACHED();
+        return true;
+    }
+
+    virtual PlatformThreadId threadId() const
+    {
+        ASSERT_NOT_REACHED();
+        return 0;
+    }
+
+    WebScheduler* scheduler() const override
+    {
+        return nullptr;
+    }
+
+    virtual void enterRunLoop()
+    {
+        ASSERT_NOT_REACHED();
+    }
+
+    virtual void exitRunLoop()
+    {
+        ASSERT_NOT_REACHED();
+    }
+};
+
+// The FakePlatform is needed on mac because ScrollAnimatorMac's constructor creates several timers.
+// We need just enough scaffolding for the Timer constructor to not segfault.
+class FakePlatform : public Platform {
+public:
+    FakePlatform() { }
+    ~FakePlatform() override { }
+
+    WebThread* currentThread() override
+    {
+        return &m_webThread;
+    }
+
+    void cryptographicallyRandomValues(unsigned char*, size_t) override
+    {
+        ASSERT_NOT_REACHED();
+    }
+
+    const unsigned char* getTraceCategoryEnabledFlag(const char*) override
+    {
+        return reinterpret_cast<const unsigned char*>("");
+    }
+
+private:
+    FakeWebThread m_webThread;
+};
+
 TEST(ScrollableAreaTest, ScrollAnimatorCurrentPositionShouldBeSync)
 {
+    Platform* oldPlatform = Platform::current();
+    FakePlatform fakePlatform;
+    Platform::initialize(&fakePlatform);
+
     MockScrollableArea scrollableArea(IntPoint(0, 100));
     scrollableArea.notifyScrollPositionChanged(IntPoint(0, 10000));
     EXPECT_EQ(100.0, scrollableArea.scrollAnimator()->currentPosition().y());
+
+    Platform::initialize(oldPlatform);
 }
 
 } // unnamed namespace