gcc 4.6 warnings cleanup

webkit/fileapi/file_system_usage_cache.cc

 // Copyright (c) 2011 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 "webkit/fileapi/file_system_usage_cache.h"
 
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/pickle.h"
 
@@ skipping 67 matching lines @@
   uint32 dirty = 0;
   int64 fs_usage;
   fs_usage = Read(usage_file_path, &is_valid, &dirty);
 
   return fs_usage >= 0 && Write(usage_file_path, false, dirty, fs_usage);
 }
 
 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;
 }
 
 // static
 int FileSystemUsageCache::AtomicUpdateUsageByDelta(
     const FilePath& usage_file_path, int64 delta) {
   bool is_valid = true;
   uint32 dirty = 0;
   int64 fs_usage;
   // TODO(dmikurube): Make sure that usage_file_path is available.
@@ skipping 71 matching lines @@
   if (bytes_written != kUsageFileSize)
     return -1;
 
   if (file_util::ReplaceFile(temporary_usage_file_path, usage_file_path))
     return bytes_written;
   else
     return -1;
 }
 
 }  // namespace fileapi