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/cmd/gomobile/strings_flag.go

Index: third_party/go/src/golang.org/x/mobile/cmd/gomobile/strings_flag.go
diff --git a/third_party/go/src/golang.org/x/mobile/cmd/gomobile/strings_flag.go b/third_party/go/src/golang.org/x/mobile/cmd/gomobile/strings_flag.go
deleted file mode 100644
index 330833e70a002beac3f80ef38aee583979df96e7..0000000000000000000000000000000000000000
--- a/third_party/go/src/golang.org/x/mobile/cmd/gomobile/strings_flag.go
+++ /dev/null
@@ -1,62 +0,0 @@
-// Copyright 2015 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 main
-
-import "fmt"
-
-type stringsFlag []string
-
-func (v *stringsFlag) Set(s string) error {
-	var err error
-	*v, err = splitQuotedFields(s)
-	if *v == nil {
-		*v = []string{}
-	}
-	return err
-}
-
-func isSpaceByte(c byte) bool {
-	return c == ' ' || c == '\t' || c == '\n' || c == '\r'
-}
-
-func splitQuotedFields(s string) ([]string, error) {
-	// Split fields allowing '' or "" around elements.
-	// Quotes further inside the string do not count.
-	var f []string
-	for len(s) > 0 {
-		for len(s) > 0 && isSpaceByte(s[0]) {
-			s = s[1:]
-		}
-		if len(s) == 0 {
-			break
-		}
-		// Accepted quoted string. No unescaping inside.
-		if s[0] == '"' || s[0] == '\'' {
-			quote := s[0]
-			s = s[1:]
-			i := 0
-			for i < len(s) && s[i] != quote {
-				i++
-			}
-			if i >= len(s) {
-				return nil, fmt.Errorf("unterminated %c string", quote)
-			}
-			f = append(f, s[:i])
-			s = s[i+1:]
-			continue
-		}
-		i := 0
-		for i < len(s) && !isSpaceByte(s[i]) {
-			i++
-		}
-		f = append(f, s[:i])
-		s = s[i:]
-	}
-	return f, nil
-}
-
-func (v *stringsFlag) String() string {
-	return "<stringsFlag>"
-}