[clang] Use -Wshorten-64-to-32 to enable warnings about 64bit to 32bit truncations.

src/base/platform/platform.h

Index: src/base/platform/platform.h
diff --git a/src/base/platform/platform.h b/src/base/platform/platform.h
index 1873bbe57d7bb96bcb31b2fe044b298ba9882de3..2d837baff61078fedd74626491dc28db8d3bf930 100644
--- a/src/base/platform/platform.h
+++ b/src/base/platform/platform.h
@@ -210,11 +210,13 @@ class OS {
 
   class MemoryMappedFile {
    public:
+    virtual ~MemoryMappedFile() {}
+    virtual void* memory() const = 0;
+    virtual size_t size() const = 0;
+
     static MemoryMappedFile* open(const char* name);
-    static MemoryMappedFile* create(const char* name, int size, void* initial);
-    virtual ~MemoryMappedFile() { }
-    virtual void* memory() = 0;
-    virtual int size() = 0;
+    static MemoryMappedFile* create(const char* name, size_t size,
+                                    void* initial);
   };
 
   // Safe formatting print. Ensures that str is always null-terminated.