Fix two unchecked return values

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 d1bc5c03fc9ca4b5259ccea5c0a0ee56e6d1cfb2..ba489be16477ebdd1fe9b1ea0b11f9c2424b7c38 100644
--- a/webkit/fileapi/file_system_usage_cache.cc
+++ b/webkit/fileapi/file_system_usage_cache.cc
@@ -4,6 +4,7 @@
 
 #include "webkit/fileapi/file_system_usage_cache.h"
 
+#include "base/compiler_specific.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/pickle.h"
@@ -86,7 +87,10 @@ bool FileSystemUsageCache::Invalidate(const FilePath& usage_file_path) {
 bool FileSystemUsageCache::IsValid(const FilePath& usage_file_path) {
   bool is_valid = true;
   uint32 dirty = 0;
-  Read(usage_file_path, &is_valid, &dirty);
+  int64 result = Read(usage_file_path, &is_valid, &dirty);
+  if (result < 0)
+    return true;

[brettw, 2012/07/26 17:38:04]

I'm not 100% sure if this is correct. Let's ask Eric

[ericu, 2012/07/26 17:58:52]

I think we want to return false there, but Kinuko or DMikurube would know for
sure.

[kinuko, 2012/07/26 18:45:31]

Looks like this should return false.  dmikurube@ can you confirm?

[Tyler Breisacher (Chromium), 2012/07/26 18:47:07]

If I'm not mistaken it's currently returning true, because we init is_valid to
true at the top. So it looks like Coverity may have helped us find an actual
bug. Hooray!

[Dai Mikurube (NOT FULLTIME), 2012/07/27 03:53:43]

I think false is fine here.

+
   return is_valid;
 }
 
@@ -163,8 +167,10 @@ int FileSystemUsageCache::Write(const FilePath& usage_file_path,
 
   DCHECK(!usage_file_path.empty());
   FilePath temporary_usage_file_path;
-  file_util::CreateTemporaryFileInDir(usage_file_path.DirName(),
-                                      &temporary_usage_file_path);
+  if (!file_util::CreateTemporaryFileInDir(usage_file_path.DirName(),
+                                           &temporary_usage_file_path))
+    return -1;
+
   int bytes_written = file_util::WriteFile(temporary_usage_file_path,
                                            (const char *)write_pickle.data(),
                                            write_pickle.size());