Move non-linux specific code from base/linux_util to app/gtk_util...

base/linux_util.h

Index: base/linux_util.h
===================================================================
--- base/linux_util.h	(revision 46986)
+++ base/linux_util.h	(working copy)
@@ -18,11 +18,6 @@
 
 static const char kFindInodeSwitch[] = "--find-inode";
 
-// Makes a copy of |pixels| with the ordering changed from BGRA to RGBA.
-// The caller is responsible for free()ing the data. If |stride| is 0,
-// it's assumed to be 4 * |width|.
-uint8_t* BGRAToRGBA(const uint8_t* pixels, int width, int height, int stride);
-
 // Get the Linux Distro if we can, or return "Unknown", similar to
 // GetWinVersion() in base/win_util.h.
 std::string GetLinuxDistro();