Make all methods on WebLayerTreeView optional.

Source/web/tests/WebFrameTest.cpp

Index: Source/web/tests/WebFrameTest.cpp
diff --git a/Source/web/tests/WebFrameTest.cpp b/Source/web/tests/WebFrameTest.cpp
index 495beab2bd55d0c12de54b67b0104a901bdddc2f..b42b5020512c68d5e568f4eb1b1add17fc2ae84d 100644
--- a/Source/web/tests/WebFrameTest.cpp
+++ b/Source/web/tests/WebFrameTest.cpp
@@ -4527,22 +4527,11 @@ public:
     CompositedSelectionBoundsTestLayerTreeView() : m_selectionCleared(false) { }
     ~CompositedSelectionBoundsTestLayerTreeView() override { }
 
-    void setRootLayer(const WebLayer&)  override { }

[pdr., 2015/08/19 23:46:01]

Can't you just copy this code in your test? I like pure virtual (or, almost
pure) because it prevents mistakes in real subclasses.

-    void clearRootLayer()  override { }
-    void setViewportSize(const WebSize& deviceViewportSize)  override { }
-    WebSize deviceViewportSize() const  override { return WebSize(); }
-    void setDeviceScaleFactor(float) override { }
-    float deviceScaleFactor() const  override { return 1.f; }
-    void setBackgroundColor(WebColor)  override { }
-    void setHasTransparentBackground(bool)  override { }
-    void setVisible(bool)  override { }
-    void setPageScaleFactorAndLimits(float pageScaleFactor, float minimum, float maximum)  override { }
-    void startPageScaleAnimation(const WebPoint& destination, bool useAnchor, float newPageScale, double durationSec)  override { }
-    void finishAllRendering()  override { }
     void registerSelection(const WebSelection& selection) override
     {
         m_selection = adoptPtr(new WebSelection(selection));
     }
+
     void clearSelection() override
     {
         m_selectionCleared = true;