Replace ErrorExit with log.Fatal in the mojom tool.

mojom/mojom_parser/check_version.go

 // Copyright 2015 The Chromium 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 (
         "crypto/sha1"
         "encoding/hex"
         "io/ioutil"
         "log"
         "path/filepath"
         "strings"
 )
 
 // checkVersion verifies the version of the mojom tool being executed
 // corresponds to the sha1 checked in source control. It works as following:
 //
 // If there is no file mojom.sha1 in the same directory as the tool, the version
 // check is bypassed.
 // If there is such a file, that files is read and it is decoded assuming that
 // it contains a hexadecimal-encoded sha1 hash. The sha1 hash of the mojom tool
 // binary being run is then computed and compared against that in the file. If
 // the comparison fails, an error message is logged and the program terminates
 // with return code 1.
 func checkVersion(args []string) {
-        // TODO(azani): Move log.SetFlags to mojom_main.go when replacing ErrorExit with log.Fatalln.
-        log.SetFlags(0)
         mojomToolPath := args[0]
         mojomDir := filepath.Dir(mojomToolPath)
         sha1FilePath := filepath.Join(mojomDir, "mojom.sha1")
 
         // First we read the file containing the sha1 hash.
         expectedSha1Bytes, err := ioutil.ReadFile(sha1FilePath)
         if err != nil {
                 // Could not read mojom.sha1. Assume it does not exist.
                 return
         }
@@ skipping 11 matching lines @@
 
         if mojomToolSha1 != expectedSha1 {
                 mojomToolAbsPath, err := filepath.Abs(mojomToolPath)
                 if err == nil {
                         mojomToolPath = mojomToolAbsPath
                 }
                 log.Fatalf("The version of the mojom tool at %s does not correspond to mojom.sha1 "+
                         "in the same directory. Please update the mojom tool (run gclient sync).\n", mojomToolPath)
         }
 }