Truncate the download file name if it exceeds the filesystem limit.

base/sys_info_posix.cc

Index: base/sys_info_posix.cc
diff --git a/base/sys_info_posix.cc b/base/sys_info_posix.cc
index f2119cd7fdb538ebc34699088387aa2381e8cc4e..d33a63c07438408f81f439f84a94502d4ebce1ef 100644
--- a/base/sys_info_posix.cc
+++ b/base/sys_info_posix.cc
@@ -50,6 +50,19 @@ int64 SysInfo::AmountOfFreeDiskSpace(const FilePath& path) {
   return static_cast<int64>(stats.f_bavail) * stats.f_frsize;
 }
 
+// static
+int SysInfo::GetMaximumPathComponentLength(const FilePath& path) {
+  base::ThreadRestrictions::AssertIOAllowed();
+  if (!path.IsAbsolute())
+    return -1;
+
+  struct statvfs stats;
+  if (statvfs(path.value().c_str(), &stats) != 0) {
+    return -1;
+  }
+  return static_cast<int>(stats.f_namemax);
+}
+
 #if !defined(OS_MACOSX) && !defined(OS_ANDROID)
 // static
 std::string SysInfo::OperatingSystemName() {