Remove log filtering and add stringsetflag.

common/logging/filter.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 logging
-
-import (
-        "flag"
-        "strings"
-)
-
-const (
-        // FilterOnAll is a Filter value that, when included in a Filter, causes it to
-        // display all log messages.
-        FilterOnAll = "all"
-
-        // FilterOnKey is a log field key whose value specifies the context's filter.
-        FilterOnKey = "_filterOn"
-)
-
-// Filter is a configurable list of strings to filter on, when the 'filterOn'
-// property is supplied.
-type Filter []string
-
-var _ flag.Value = (*Filter)(nil)
-
-// Set implements flag.Value.
-func (f *Filter) Set(v string) error {
-        if len(v) > 0 {
-                *f = append(*f, v)
-        }
-        return nil
-}
-
-// String implements flag.Value.
-func (f *Filter) String() string {
-        return strings.Join([]string(*f), ",")
-}
-
-// Get returns a filter function that returns true if the Filter passes the
-// supplied log flags.
-func (f Filter) Get() func(interface{}) bool {
-        filterMap := make(map[string]bool)
-        for _, filter := range f {
-                if filter == FilterOnAll {
-                        filterMap = nil
-                        break
-                }
-                filterMap[filter] = true
-        }
-
-        return func(filterOn interface{}) bool {
-                if filterMap == nil || filterOn == nil {
-                        return true
-                }
-
-                switch t := filterOn.(type) {
-                case string:
-                        _, ok := filterMap[t]
-                        return ok
-
-                default:
-                        return true
-                }
-        }
-}