Move gtk_settings_get_default() call to the UI thread.

chrome/browser/icon_loader.cc

Index: chrome/browser/icon_loader.cc
===================================================================
--- chrome/browser/icon_loader.cc	(revision 23879)
+++ chrome/browser/icon_loader.cc	(working copy)
@@ -5,6 +5,7 @@
 #include "chrome/browser/icon_loader.h"
 
 #include "base/message_loop.h"
+#include "base/mime_util.h"
 #include "base/thread.h"
 #include "chrome/browser/browser_process.h"
 #include "third_party/skia/include/core/SkBitmap.h"
@@ -24,6 +25,11 @@
 void IconLoader::Start() {
   target_message_loop_ = MessageLoop::current();
 
+#if defined(OS_LINUX)
+  // This call must happen on the UI thread before we can start loading icons.
+  mime_util::DetectGtkTheme();
+#endif
+
   g_browser_process->file_thread()->message_loop()->PostTask(FROM_HERE,
       NewRunnableMethod(this, &IconLoader::ReadIcon));
 }