Fix Linux build failure caused by GCC 4.3/4.2 differences.

chrome/common/gfx/favicon_size.h

Index: chrome/common/gfx/favicon_size.h
===================================================================
--- chrome/common/gfx/favicon_size.h	(revision 7061)
+++ chrome/common/gfx/favicon_size.h	(working copy)
@@ -5,9 +5,15 @@
 #ifndef CHROME_COMMON_GFX_FAVICON_SIZE_H__
 #define CHROME_COMMON_GFX_FAVICON_SIZE_H__
 
+#include "build/build_config.h"
+
 // Size (along each axis) of the favicon.
 const int kFavIconSize = 16;
 
+#if !defined(OS_LINUX)
+// GCC 4.2 complains that this function is not used, and currently
+// it's not used by any file compiled on Linux. GCC 4.3 does not complain.
+
 // If the width or height is bigger than the favicon size, a new width/height
 // is calculated and returned in width/height that maintains the aspect
 // ratio of the supplied values.
@@ -25,5 +31,7 @@
   }
 }
 
+#endif  // !defined(OS_LINUX)
+
 #endif // CHROME_COMMON_GFX_FAVICON_SIZE_H__