Remove third_party/golang.org/x/mobile as it is no longer used with Go 1.5.

third_party/go/src/golang.org/x/mobile/font/font_android.go

Index: third_party/go/src/golang.org/x/mobile/font/font_android.go
diff --git a/third_party/go/src/golang.org/x/mobile/font/font_android.go b/third_party/go/src/golang.org/x/mobile/font/font_android.go
deleted file mode 100644
index 3503ec991e088dcb8a958f5aa92d8b8eab105f07..0000000000000000000000000000000000000000
--- a/third_party/go/src/golang.org/x/mobile/font/font_android.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// Copyright 2014 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package font
-
-import "io/ioutil"
-
-func buildDefault() ([]byte, error) {
-	return ioutil.ReadFile("/system/fonts/DroidSans.ttf")
-}
-
-func buildMonospace() ([]byte, error) {
-	return ioutil.ReadFile("/system/fonts/DroidSansMono.ttf")
-}