Implement timers by posting delayed 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..68794648ae04333b0c68e583f7e9d7ba2d42089d 100644
--- a/Source/platform/scroll/ScrollableAreaTest.cpp
+++ b/Source/platform/scroll/ScrollableAreaTest.cpp
@@ -6,6 +6,10 @@
 
 #include "platform/scroll/ScrollableArea.h"
 
+#include "platform/TestingPlatformSupport.h"
+#include "public/platform/Platform.h"
+#include "public/platform/WebScheduler.h"
+#include "public/platform/WebThread.h"
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
@@ -47,7 +51,70 @@ private:
     IntPoint m_maximumScrollPosition;
 };
 
-TEST(ScrollableAreaTest, ScrollAnimatorCurrentPositionShouldBeSync)
+class FakeWebThread : public WebThread {
+public:
+    FakeWebThread() { }
+    ~FakeWebThread() override { }
+
+    void postTask(const WebTraceLocation&, Task*) override
+    {
+        ASSERT_NOT_REACHED();
+    }
+
+    void postDelayedTask(const WebTraceLocation&, Task*, long long) override
+    {
+        ASSERT_NOT_REACHED();
+    }
+
+    bool isCurrentThread() const override
+    {
+        ASSERT_NOT_REACHED();
+        return true;
+    }
+
+    WebScheduler* scheduler() const override
+    {
+        return nullptr;
+    }
+};
+
+// The FakePlatform is needed because ScrollAnimatorMac's constructor creates several timers.
+// We need just enough scaffolding for the Timer constructor to not segfault.
+class FakePlatform : public TestingPlatformSupport {
+public:
+    FakePlatform() : TestingPlatformSupport(TestingPlatformSupport::Config()) { }
+    ~FakePlatform() override { }
+
+    WebThread* currentThread() override
+    {
+        return &m_webThread;
+    }
+
+private:
+    FakeWebThread m_webThread;
+};
+
+class ScrollableAreaTest : public testing::Test {
+public:
+    ScrollableAreaTest() : m_oldPlatform(nullptr) { }
+
+    void SetUp() override
+    {
+        m_oldPlatform = Platform::current();
+        Platform::initialize(&m_fakePlatform);
+    }
+
+    void TearDown() override
+    {
+        Platform::initialize(m_oldPlatform);
+    }
+
+private:
+    FakePlatform m_fakePlatform;
+    Platform* m_oldPlatform; // Not owned.
+};
+
+TEST_F(ScrollableAreaTest, ScrollAnimatorCurrentPositionShouldBeSync)
 {
     MockScrollableArea scrollableArea(IntPoint(0, 100));
     scrollableArea.notifyScrollPositionChanged(IntPoint(0, 10000));
@@ -55,5 +122,3 @@ TEST(ScrollableAreaTest, ScrollAnimatorCurrentPositionShouldBeSync)
 }
 
 } // unnamed namespace
-
-