Make container classes in SkTemplates.h more consistent

include/private/SkTemplates.h

Index: include/private/SkTemplates.h
diff --git a/include/private/SkTemplates.h b/include/private/SkTemplates.h
index 7e2c19f09daa199486462e0410f64a79a58cce2c..3ca5978cbb5578561e59db28b5e123d57b6bf23f 100644
--- a/include/private/SkTemplates.h
+++ b/include/private/SkTemplates.h
@@ -326,8 +326,11 @@ public:
     SkAutoSTMalloc(size_t count) {
         if (count > kCount) {
             fPtr = (T*)sk_malloc_flags(count * sizeof(T), SK_MALLOC_THROW | SK_MALLOC_TEMP);
-        } else {
+        } else if (count > 0) {
             fPtr = fTStorage;
+        } else {
+            SkASSERT(0 == count);

[reed1, 2016/06/22 11:33:30]

Can this ever not be true?

[csmartdalton, 2016/06/23 17:07:46]

The idea would be that if somebody unintentionally calls this with a negative
number it helps them find their bug. Of course, it's already making the pointer
null, which would bring it to their attention pretty quickly anyway.

[reed1, 2016/06/23 17:44:36]

but count is size_t, which will never appear to be negative

[csmartdalton, 2016/06/23 18:07:26]

Yeah, I realized it was size_t after the fact :)

+            fPtr = nullptr;
         }
     }
 
@@ -344,8 +347,11 @@ public:
         }
         if (count > kCount) {
             fPtr = (T*)sk_malloc_throw(count * sizeof(T));
-        } else {
+        } else if (count > 0) {
             fPtr = fTStorage;
+        } else {
+            SkASSERT(0 == count);
+            fPtr = nullptr;
         }
         return fPtr;
     }