[errors] Remove Fix(), move MultiErrorFromErrors().

common/errors/annotate_example_test.go

 // Copyright 2016 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package errors
 
 import (
         "fmt"
 )
 
@@ skipping 32 matching lines @@
         }
         return err
 }
 
 func someIntermediateFunc(vals ...int) error {
         errch := make(chan error)
         go func() {
                 defer close(errch)
                 errch <- Annotate(errorWrapper(someLibFunc(vals...))).Reason("could not process").Err()
         }()
-        if err := MultiErrorFromErrors(errch); err != nil {
-                return Annotate(err).Reason("while processing %(vals)v").D("vals", vals).Err()
+        me := MultiError(nil)
+        for err := range errch {
+                if err != nil {
+                        me = append(me, err)
+                }
+        }
+        if me != nil {
+                return Annotate(me).Reason("while processing %(vals)v").D("vals", vals).Err()
         }
         return nil
 }
 
 func ExampleAnnotate() {
         if err := someIntermediateFunc(3); err != nil {
                 err = Annotate(err).Reason("top level").Err()
                 fmt.Println("Public-facing error:\n ", err)
                 fmt.Println("\nfull error:")
                 for _, l := range FixForTest(RenderStack(err).ToLines("runtime", "_test")) {
@@ skipping 30 matching lines @@
         //   MultiError 1/1: following first non-nil error.
         //     "non-nil" = 1
         //     "total" = 1
         //
         // #? github.com/luci/luci-go/common/errors/annotate_example_test.go:51 - errors.someIntermediateFunc.func1()
         //   reason: "could not process"
         //
         // ... skipped SOME frames in pkg "runtime"...
         //
         // GOROUTINE LINE
-        // #? github.com/luci/luci-go/common/errors/annotate_example_test.go:54 - errors.someIntermediateFunc()
+        // #? github.com/luci/luci-go/common/errors/annotate_example_test.go:60 - errors.someIntermediateFunc()
         //   reason: "while processing [3]"
         //   "vals" = []int{3}
         //
-        // #? github.com/luci/luci-go/common/errors/annotate_example_test.go:60 - errors.ExampleAnnotate()
+        // #? github.com/luci/luci-go/common/errors/annotate_example_test.go:66 - errors.ExampleAnnotate()
         //   reason: "top level"
         //
         // #? testing/example.go:XXX - testing.runExample()
         // #? testing/example.go:XXX - testing.runExamples()
         // #? testing/testing.go:XXX - testing.(*M).Run()
         // ... skipped SOME frames in pkg "_test"...
         // ... skipped SOME frames in pkg "runtime"...
-
 }