Formatter: Avoid extraneous empty lines at the end of a block.

mojom/mojom_parser/formatter/printer.go

 // Copyright 2016 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 formatter
 
 import (
         "bytes"
         "fmt"
         "mojom/mojom_parser/lexer"
@@ skipping 556 matching lines @@
         if attachedComments == nil {
                 return
         }
 
         p.writeCommentBlocks(attachedComments.Above, true)
 }
 
 func (p *printer) writeFinalComments(container mojom.DeclaredObjectsContainer) {
         el := container.(mojom.MojomElement)
         attachedComments := el.AttachedComments()
-        if attachedComments == nil || len(attachedComments.Final) == 0 {
+        if attachedComments == nil {
+                return
+        }
+        finalComments := trimEmptyLinesEnd(attachedComments.Final)
+        if len(finalComments) == 0 {
                 return
         }
 
         // Only print blank lines if there is something other than comments in the
         // container.
         if len(container.GetDeclaredObjects()) > 0 {
                 p.nl()
-                if attachedComments.Final[0].Kind == lexer.EmptyLine {
+                if finalComments[0].Kind == lexer.EmptyLine {
                         p.nl()
                 }
         }
-        p.writeCommentBlocks(attachedComments.Final, false)
+        p.writeCommentBlocks(finalComments, false)
 }
 
 // writeLeftComments writes the comments left of a MojomElement.
 func (p *printer) writeLeftComments(el mojom.MojomElement) {
         attachedComments := el.AttachedComments()
         if attachedComments == nil {
                 return
         }
 
         for _, comment := range attachedComments.Left {
@@ skipping 344 matching lines @@
 
 // See sort.Interface.
 func (ifs *importedFilesSorter) Less(i, j int) bool {
         return ifs.imports[i].SpecifiedName < ifs.imports[j].SpecifiedName
 }
 
 // See sort.Interface.
 func (ifs *importedFilesSorter) Swap(i, j int) {
         ifs.imports[i], ifs.imports[j] = ifs.imports[j], ifs.imports[i]
 }