gcc 4.6 warnings cleanup

webkit/fileapi/file_system_usage_cache.cc

Index: webkit/fileapi/file_system_usage_cache.cc
diff --git a/webkit/fileapi/file_system_usage_cache.cc b/webkit/fileapi/file_system_usage_cache.cc
index 4ac3a1b098a2f97445db294ee5a02a4e7a96e7e8..46bbdff669eeaafbf46c923c51503058becc57c2 100644
--- a/webkit/fileapi/file_system_usage_cache.cc
+++ b/webkit/fileapi/file_system_usage_cache.cc
@@ -85,8 +85,7 @@ bool FileSystemUsageCache::Invalidate(const FilePath& usage_file_path) {
 bool FileSystemUsageCache::IsValid(const FilePath& usage_file_path) {
   bool is_valid = true;
   uint32 dirty = 0;
-  int64 fs_usage;
-  fs_usage = Read(usage_file_path, &is_valid, &dirty);
+  Read(usage_file_path, &is_valid, &dirty);
   return is_valid;
 }