Make code compile with clang_use_chrome_plugin (part I)

core/fpdfapi/fpdf_page/include/cpdf_pageobject.h

Index: core/fpdfapi/fpdf_page/include/cpdf_pageobject.h
diff --git a/core/fpdfapi/fpdf_page/include/cpdf_pageobject.h b/core/fpdfapi/fpdf_page/include/cpdf_pageobject.h
index 8e7da81e907a564e2b9291c3722c3bd9e635cc37..d9d584388e47e0242915e196997e6ea35b9b9ce3 100644
--- a/core/fpdfapi/fpdf_page/include/cpdf_pageobject.h
+++ b/core/fpdfapi/fpdf_page/include/cpdf_pageobject.h
@@ -29,26 +29,26 @@ class CPDF_PageObject : public CPDF_GraphicStates {
   };
 
   CPDF_PageObject();
-  virtual ~CPDF_PageObject();
+  ~CPDF_PageObject() override;
 
   virtual CPDF_PageObject* Clone() const = 0;
   virtual Type GetType() const = 0;
   virtual void Transform(const CFX_Matrix& matrix) = 0;
-  virtual bool IsText() const { return false; }
-  virtual bool IsPath() const { return false; }
-  virtual bool IsImage() const { return false; }
-  virtual bool IsShading() const { return false; }
-  virtual bool IsForm() const { return false; }
-  virtual CPDF_TextObject* AsText() { return nullptr; }
-  virtual const CPDF_TextObject* AsText() const { return nullptr; }
-  virtual CPDF_PathObject* AsPath() { return nullptr; }
-  virtual const CPDF_PathObject* AsPath() const { return nullptr; }
-  virtual CPDF_ImageObject* AsImage() { return nullptr; }
-  virtual const CPDF_ImageObject* AsImage() const { return nullptr; }
-  virtual CPDF_ShadingObject* AsShading() { return nullptr; }
-  virtual const CPDF_ShadingObject* AsShading() const { return nullptr; }
-  virtual CPDF_FormObject* AsForm() { return nullptr; }
-  virtual const CPDF_FormObject* AsForm() const { return nullptr; }
+  virtual bool IsText() const;
+  virtual bool IsPath() const;
+  virtual bool IsImage() const;
+  virtual bool IsShading() const;
+  virtual bool IsForm() const;
+  virtual CPDF_TextObject* AsText();
+  virtual const CPDF_TextObject* AsText() const;
+  virtual CPDF_PathObject* AsPath();
+  virtual const CPDF_PathObject* AsPath() const;
+  virtual CPDF_ImageObject* AsImage();
+  virtual const CPDF_ImageObject* AsImage() const;
+  virtual CPDF_ShadingObject* AsShading();
+  virtual const CPDF_ShadingObject* AsShading() const;
+  virtual CPDF_FormObject* AsForm();
+  virtual const CPDF_FormObject* AsForm() const;
 
   void TransformClipPath(CFX_Matrix& matrix);
   void TransformGeneralState(CFX_Matrix& matrix);