Fix -Wnon-virtual-dtor compiler warnings.

This is done by explicitly adding a virtual dtor to interface classes,
since the cost is small given that there are already virtual functions.

The exceptions are for classes that have a Release() or Delete() method,
in which case it is non-virtual and protected to indicate that the virtual
class is never the deletion point.

BUG=
R=brucedawson@chromium.org, thestig@chromium.org

Review URL: https://codereview.chromium.org/810883005

3 files changed, 7 insertions, 4 deletions

diff --git a/core/include/fpdfdoc/fpdf_ap.h b/core/include/fpdfdoc/fpdf_ap.h
index 78f9676221..02bbf249c4 100644
--- a/core/include/fpdfdoc/fpdf_ap.h
+++ b/core/include/fpdfdoc/fpdf_ap.h
@@ -13,9 +13,8 @@
 class IPVT_FontMap
 {
 public:
-
+    virtual ~IPVT_FontMap() { }
     virtual CPDF_Font*						GetPDFFont(FX_INT32 nFontIndex) = 0;
-
     virtual CFX_ByteString					GetPDFFontAlias(FX_INT32 nFontIndex) = 0;
 };
 struct CPVT_Dash {
diff --git a/core/include/fpdfdoc/fpdf_tagged.h b/core/include/fpdfdoc/fpdf_tagged.h
index f3ab01ea28..1a2a5d4ffa 100644
--- a/core/include/fpdfdoc/fpdf_tagged.h
+++ b/core/include/fpdfdoc/fpdf_tagged.h
@@ -68,6 +68,7 @@ struct CPDF_StructKid {
 class CPDF_StructElement : public CFX_Object
 {
 public:
+    virtual ~CPDF_StructElement() { }
 
     virtual CPDF_StructTree*	GetTree() const = 0;
 
diff --git a/core/include/fpdfdoc/fpdf_vt.h b/core/include/fpdfdoc/fpdf_vt.h
index 41025cbe2e..3e23c3a1a3 100644
--- a/core/include/fpdfdoc/fpdf_vt.h
+++ b/core/include/fpdfdoc/fpdf_vt.h
@@ -275,6 +275,7 @@ struct CPVT_Section {
 class IPDF_VariableText_Provider
 {
 public:
+    virtual ~IPDF_VariableText_Provider() { }
 
     virtual FX_INT32						GetCharWidth(FX_INT32 nFontIndex, FX_WORD word, FX_INT32 nWordStyle) = 0;
 
@@ -291,6 +292,7 @@ public:
 class IPDF_VariableText_Iterator
 {
 public:
+    virtual ~IPDF_VariableText_Iterator() { }
 
     virtual FX_BOOL							NextWord() = 0;
 
@@ -323,11 +325,9 @@ public:
 class IPDF_VariableText
 {
 public:
-
     static IPDF_VariableText*			NewVariableText();
 
     static void							DelVariableText(IPDF_VariableText* pVT);
-public:
 
     virtual IPDF_VariableText_Provider*		SetProvider(IPDF_VariableText_Provider * pProvider) = 0;
 
@@ -440,5 +440,8 @@ public:
     virtual FX_INT32						WordPlaceToWordIndex(const CPVT_WordPlace & place) const = 0;
 
     virtual CPVT_WordPlace					WordIndexToWordPlace(FX_INT32 index) const = 0;
+
+protected:
+    ~IPDF_VariableText() { }
 };
 #endif