Prevent crashes in mime_util_xdg.

base/nix/mime_util_xdg.cc

Index: base/nix/mime_util_xdg.cc
diff --git a/base/nix/mime_util_xdg.cc b/base/nix/mime_util_xdg.cc
index 030c30c11f6559361aed3757461a2d89d4268b95..e58e03dca1e0c04f433ee2ec86088eac41347018 100644
--- a/base/nix/mime_util_xdg.cc
+++ b/base/nix/mime_util_xdg.cc
@@ -588,6 +588,8 @@ namespace base {
 namespace nix {
 
 std::string GetFileMimeType(const FilePath& filepath) {
+  if (filepath.empty())

[Lei Zhang, 2012/08/22 05:59:10]

Curious, who is calling GetFileMimeType with an empty filepath?
IconManager::LoadIcon() ?

[benjhayden, 2012/08/22 14:24:14]

Yes, LoadIcon() doesn't early-return for empty paths, iirc.
No, nothing is currently calling LoadIcon() with an empty path, afaik. We're
currently refactoring the downloads system, and in a few of my recent refactors,
I had bugs where I was calling LoadIcon() with an empty path. I fixed the bugs,
but until I get around to writing a lot more tests, it could easily come back,
and I'd rather display a blank icon than crash.

+    return std::string();
   base::ThreadRestrictions::AssertIOAllowed();
   base::AutoLock scoped_lock(g_mime_util_xdg_lock.Get());
   return xdg_mime_get_mime_type_from_file_name(filepath.value().c_str());
@@ -625,7 +627,7 @@ FilePath GetMimeIcon(const std::string& mime_type, size_t size) {
   std::string icon_name;
   FilePath icon_file;
 
-  {
+  if (!mime_type.empty()) {
     base::AutoLock scoped_lock(g_mime_util_xdg_lock.Get());
     const char *icon = xdg_mime_get_icon(mime_type.c_str());
     icon_name = std::string(icon ? icon : "");