Enable size_t to int truncation warnings in PPAPI

ppapi/shared_impl/flash_clipboard_format_registry.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ppapi/shared_impl/flash_clipboard_format_registry.h"
 
 #include <cctype>
 
 namespace ppapi {
 
@@ skipping 25 matching lines @@
 FlashClipboardFormatRegistry::FlashClipboardFormatRegistry() {}
 
 FlashClipboardFormatRegistry::~FlashClipboardFormatRegistry() {}
 
 uint32_t FlashClipboardFormatRegistry::RegisterFormat(
     const std::string& format_name) {
   if (!IsValidFormatName(format_name) ||
       custom_formats_.size() > kMaxNumFormats) {
     return PP_FLASH_CLIPBOARD_FORMAT_INVALID;
   }
-  uint32_t key = kFirstCustomFormat + custom_formats_.size();
+  uint32_t key = kFirstCustomFormat +
+                 static_cast<uint32_t>(custom_formats_.size());
   custom_formats_[key] = format_name;
   return key;
 }
 
 void FlashClipboardFormatRegistry::SetRegisteredFormat(
     const std::string& format_name,
     uint32_t format) {
   custom_formats_[format] = format_name;
 }
 
@@ skipping 20 matching lines @@
 }
 
 // static
 bool FlashClipboardFormatRegistry::IsValidPredefinedFormat(uint32_t format) {
   if (format == PP_FLASH_CLIPBOARD_FORMAT_INVALID)
     return false;
   return format < kFirstCustomFormat;
 }
 
 }  // namespace ppapi