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

src/base/platform/platform.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This module contains the platform-specific code. This make the rest of the
 // code less dependent on operating system, compilers and runtime libraries.
 // This module does specifically not deal with differences between different
 // processor architecture.
 // The platform classes have the same definition for all platforms. The
 // implementation for a particular platform is put in platform_<os>.cc.
@@ skipping 192 matching lines @@
   static const int kStackWalkError = -1;
   static const int kStackWalkMaxNameLen = 256;
   static const int kStackWalkMaxTextLen = 256;
   struct StackFrame {
     void* address;
     char text[kStackWalkMaxTextLen];
   };
 
   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.
   // Returns the number of chars written, or -1 if output was truncated.
   static int SNPrintF(char* str, int length, const char* format, ...);
   static int VSNPrintF(char* str,
                        int length,
                        const char* format,
                        va_list args);
 
@@ skipping 240 matching lines @@
   char name_[kMaxThreadNameLength];
   int stack_size_;
   Semaphore* start_semaphore_;
 
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 } }  // namespace v8::base
 
 #endif  // V8_BASE_PLATFORM_PLATFORM_H_