aura: Make the Linux version of IconLoader not require GTK+.

net/base/platform_mime_util_linux.cc

Index: net/base/platform_mime_util_linux.cc
diff --git a/net/base/platform_mime_util_linux.cc b/net/base/platform_mime_util_linux.cc
index c841914dde778d9ac6850620f3e910382ac1d7f7..1d4acc037949ba133f6c5199d662d0789d9bd2ef 100644
--- a/net/base/platform_mime_util_linux.cc
+++ b/net/base/platform_mime_util_linux.cc
@@ -22,12 +22,6 @@ bool PlatformMimeUtil::GetPlatformMimeTypeFromExtension(
     const FilePath::StringType& ext, std::string* result) const {
   return android::GetMimeTypeFromExtension(ext, result);
 }
-#elif defined(USE_AURA)
-bool PlatformMimeUtil::GetPlatformMimeTypeFromExtension(
-    const FilePath::StringType& ext, std::string* result) const {
-  NOTIMPLEMENTED();
-  return false;
-}
 #else
 bool PlatformMimeUtil::GetPlatformMimeTypeFromExtension(
     const FilePath::StringType& ext, std::string* result) const {