pdfium: Fix all -Wdelete-non-virtual-dtor violations on Mac.

Calling `delete` on an object of a type that has virtual functions but
not a virtual destructor is questionable: Since the object has virtual functions,
it likely has subclasses, so if it's deleted through the base pointer and the
destructor isn't virtual, the subclass destructor won't be called.

In most cases, the classes getting deleted can just be marked final to tell
the compiler that it can't possibly have subclasses (this also enables the
compiler to generate better code).

Two classes didn't have any sub- or superclasses but virtual functions -
this doesn't make sense, so make all methods of these classes non-virtual.
(Also delete an unused function on one of the two classes.)

In one case, a class actually did have a subclass that needs to be deleted
virtually, so mark one destructor as virtual.

BUG=none
R=bo_xu@foxitsoftware.com

Review URL: https://codereview.chromium.org/370853002

1 files changed, 9 insertions, 0 deletions

diff --git a/core/include/fxcrt/fx_system.h b/core/include/fxcrt/fx_system.h
index 9f43360fa7..a757de4c5e 100644
--- a/core/include/fxcrt/fx_system.h
+++ b/core/include/fxcrt/fx_system.h
@@ -275,5 +275,14 @@ int			FXSYS_round(FX_FLOAT f);
 #define		FXSYS_sqrt2(a, b) (FX_FLOAT)FXSYS_sqrt((a)*(a) + (b)*(b))
 #ifdef __cplusplus
 };
+
+#if defined(__clang__) || defined(_MSC_VER)
+#define FX_FINAL final
+#elif defined(__GNUC__) && __cplusplus >= 201103 && \
+      (__GNUC__ * 10000 + __GNUC_MINOR__ * 100) >= 40700
+#define FX_FINAL final
+#else
+#define FX_FINAL
+#endif
 #endif
 #endif