fix warnings around size_t/int

src/core/SkDescriptor.h

Index: src/core/SkDescriptor.h
diff --git a/src/core/SkDescriptor.h b/src/core/SkDescriptor.h
index e71ff41b5c5412a9382d36b7c78ea919b2cf7be2..c526451af5e68e80ff44253f0dde89a7cef457b1 100644
--- a/src/core/SkDescriptor.h
+++ b/src/core/SkDescriptor.h
@@ -37,14 +37,14 @@ public:
 
     uint32_t getLength() const { return fLength; }
 
-    void* addEntry(uint32_t tag, uint32_t length, const void* data = NULL) {
+    void* addEntry(uint32_t tag, size_t length, const void* data = NULL) {
         SkASSERT(tag);
         SkASSERT(SkAlign4(length) == length);
         SkASSERT(this->findEntry(tag, NULL) == NULL);
 
         Entry*  entry = (Entry*)((char*)this + fLength);
         entry->fTag = tag;
-        entry->fLen = length;
+        entry->fLen = SkToU32(length);
         if (data) {
             memcpy(entry + 1, data, length);
         }