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..30942ad991675d287785b258cd57324093945e11 100644
--- a/include/private/SkTemplates.h
+++ b/include/private/SkTemplates.h
@@ -209,6 +209,7 @@ public:
             } else if (count > 0) {
                 fArray = (T*) fStorage;
             } else {
+                SkASSERT(0 == count);

[bsalomon, 2016/06/23 17:53:34]

I think it'd be slightly clearer to just put SkASSERT(count >= 0); at the top of
the function.

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

Done.

                 fArray = NULL;
             }
 
@@ -267,7 +268,7 @@ public:
 
     /** Allocates space for 'count' Ts. */
     explicit SkAutoTMalloc(size_t count) {
-        fPtr = (T*)sk_malloc_flags(count * sizeof(T), SK_MALLOC_THROW);
+        fPtr = count ? (T*)sk_malloc_flags(count * sizeof(T), SK_MALLOC_THROW) : nullptr;
     }
 
     ~SkAutoTMalloc() {
@@ -326,8 +327,10 @@ 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) {
             fPtr = fTStorage;
+        } else {
+            fPtr = nullptr;
         }
     }
 
@@ -344,8 +347,10 @@ public:
         }
         if (count > kCount) {
             fPtr = (T*)sk_malloc_throw(count * sizeof(T));
-        } else {
+        } else if (count) {
             fPtr = fTStorage;
+        } else {
+            fPtr = nullptr;
         }
         return fPtr;
     }