cc: Only allow trees created at the current viewport size to draw.

cc/layer_tree_host_impl.h

Index: cc/layer_tree_host_impl.h
diff --git a/cc/layer_tree_host_impl.h b/cc/layer_tree_host_impl.h
index b95607494b9663b0a36a058f7081fa06f4bf20ac..205e0d803968ca16ec4a31c194ce077afddd2e5b 100644
--- a/cc/layer_tree_host_impl.h
+++ b/cc/layer_tree_host_impl.h
@@ -186,7 +186,7 @@ public:
     size_t memoryAllocationLimitBytes() const { return m_managedMemoryPolicy.bytesLimitWhenVisible; }
 
     void setViewportSize(const gfx::Size& layoutViewportSize, const gfx::Size& deviceViewportSize);
-    const gfx::Size& layoutViewportSize() const { return m_layoutViewportSize; }
+    const gfx::Size& layoutViewportSize() const;
 
     float deviceScaleFactor() const { return m_deviceScaleFactor; }
     void setDeviceScaleFactor(float);
@@ -332,8 +332,6 @@ private:
     bool m_wheelScrolling;
     LayerTreeSettings m_settings;
     LayerTreeDebugState m_debugState;
-    gfx::Size m_layoutViewportSize;
-    gfx::Size m_deviceViewportSize;
     float m_deviceScaleFactor;
     bool m_visible;
     ManagedMemoryPolicy m_managedMemoryPolicy;