Add virtual destructor for GrDrawTargetCaps

src/gpu/GrDrawTargetCaps.h

Index: src/gpu/GrDrawTargetCaps.h
diff --git a/src/gpu/GrDrawTargetCaps.h b/src/gpu/GrDrawTargetCaps.h
index 0f7a712dc65ee7b06963f4cb76d74898cb1b6afc..086b61579a82e0dfe418cf0bd8a11f82ae691de5 100644
--- a/src/gpu/GrDrawTargetCaps.h
+++ b/src/gpu/GrDrawTargetCaps.h
@@ -116,6 +116,7 @@ public:
     GrDrawTargetCaps(const GrDrawTargetCaps& other) : INHERITED() {
         *this = other;
     }
+    virtual ~GrDrawTargetCaps() {}
     GrDrawTargetCaps& operator= (const GrDrawTargetCaps&);
 
     virtual void reset();