Checks the possibility of overscans from EDID extension data.

ui/base/x/x11_util.h

Index: ui/base/x/x11_util.h
diff --git a/ui/base/x/x11_util.h b/ui/base/x/x11_util.h
index e7169a6f0d1515dd2fdf21f95194dabb87292cb3..a5b8beccd9aa63077c5a657b8d0e220b45a0d02a 100644
--- a/ui/base/x/x11_util.h
+++ b/ui/base/x/x11_util.h
@@ -276,6 +276,25 @@ UI_EXPORT bool GetOutputDeviceData(XID output,
                                    uint32* serial_number,
                                    std::string* human_readable_name);
 
+// Returns true if the EDID for the output has the flag of overscan. Note that

[Daniel Erat, 2013/01/04 00:19:12]

nit: s/the flag of overscan/its overscan flag set/

[Jun Mukai, 2013/01/04 01:43:01]

Done.

+// returning false does not mean no overscan, it just means the lack of flag.

[Daniel Erat, 2013/01/04 00:19:12]

nit: s/no overscan/overscan is disabled/, s/lack of flag/flag wasn't present/

[Jun Mukai, 2013/01/04 01:43:01]

Hmm, 'overscan is disabled' sounds like a bit weird to me.
I rewrote the whole comment, so please take another look. Sorry!

+UI_EXPORT bool HasOutputOverscanFlag(XID output);

[Daniel Erat, 2013/01/04 00:19:12]

nit: sorry for conflicting with an earlier suggestion, but a name like
OutputOverscanFlagIsSet() might be better, since this is really testing both
that the has the flag and that the flag is set -- Has...Flag() seems like it
could also return true if the flag was there but was set to false.

[Jun Mukai, 2013/01/04 01:43:01]

I also changed my mind and it would be good to distinguish the existence of the
flag and the contents of the flag. So it's consistent with
GetOutputDeviceData(), and renamed it to bool GetOutputOverscanFlag(XID, bool*);

+
+// Parses |prop| as EDID data and stores extracted data into |manufacturer_id|,
+// |serial_number|, and |human_readable_name| and returns true. This is exported
+// for x11_util_unittest.cc.

[Daniel Erat, 2013/01/04 00:19:12]

nit: document that the last three arguments can be NULL if the caller doesn't
care about the values

[Jun Mukai, 2013/01/04 01:43:01]

Done.

+UI_EXPORT bool ParseOutputDeviceData(const unsigned char* prop,
+                                     unsigned long nitems,
+                                     uint16* manufacturer_id,
+                                     uint32* serial_number,
+                                     std::string* human_readable_name);
+
+// Parses |prop| as EDID data and stores overscan flag to |flag|. Returns true
+// if the flag is found. This is exported for x11_util_unittest.cc.
+UI_EXPORT bool ParseOutputOverscanFlag(const unsigned char* prop,
+                                       unsigned long nitems,
+                                       bool* flag);
+
 // Gets the names of the all displays physically connected to the system.
 UI_EXPORT std::vector<std::string> GetDisplayNames(
     const std::vector<XID>& output_id);