metrics/base: log whether drives have seek penalties.

base/sys_info.h

Index: base/sys_info.h
diff --git a/base/sys_info.h b/base/sys_info.h
index 660343d06f76831b2f6dceff35cce4bb40e212c0..f639ae4958cce075d11d4b09b185780d1be31585 100644
--- a/base/sys_info.h
+++ b/base/sys_info.h
@@ -48,6 +48,11 @@ class BASE_EXPORT SysInfo {
   // or -1 on failure.
   static int64 AmountOfFreeDiskSpace(const FilePath& path);
 
+  // Determine whether the device that services |path| has a seek penalty.
+  // Returns false if it couldn't be determined (e.g., |path| doesn't exist) or
+  // |has_seek_penalty| is NULL.

[rvargas (doing something else), 2015/03/12 22:01:11]

The second condition sounds like a DCHECK to me.

[Dan Beam, 2015/03/13 19:31:31]

Done.

+  static bool HasSeekPenalty(const FilePath& path, bool* has_seek_penalty);
+
   // Returns system uptime in milliseconds.
   static int64 Uptime();