Sort "deps" and "public_deps" when running the "gn format" command.

tools/gn/command_format.cc

Index: tools/gn/command_format.cc
diff --git a/tools/gn/command_format.cc b/tools/gn/command_format.cc
index 5eff6017f3f9c2f4a4574e852e7e0ca0373d2d0c..ef3149ef219098ed4395c40ab7bff158b0baf391 100644
--- a/tools/gn/command_format.cc
+++ b/tools/gn/command_format.cc
@@ -128,8 +128,8 @@ class Printer {
   // Flag assignments to sources, deps, etc. to make their RHSs multiline.
   void AnnotatePreferredMultilineAssignment(const BinaryOpNode* binop);
 
-  // Alphabetically a list on the RHS if the LHS is 'sources'.
-  void SortIfSources(const BinaryOpNode* binop);
+  // Alphabetically a list on the RHS if the LHS is 'sources' or 'deps'.
+  void SortIfSourcesOrDeps(const BinaryOpNode* binop);
 
   // Heuristics to decide if there should be a blank line added between two
   // items. For various "small" items, it doesn't look nice if there's too much
@@ -307,15 +307,15 @@ void Printer::AnnotatePreferredMultilineAssignment(const BinaryOpNode* binop) {
   }
 }
 
-void Printer::SortIfSources(const BinaryOpNode* binop) {
+void Printer::SortIfSourcesOrDeps(const BinaryOpNode* binop) {
   const IdentifierNode* ident = binop->left()->AsIdentifier();
   const ListNode* list = binop->right()->AsList();
-  // TODO(scottmg): Sort more than 'sources'?
+  // TODO(scottmg): Sort more than 'sources' and 'deps'?
   if ((binop->op().value() == "=" || binop->op().value() == "+=" ||
        binop->op().value() == "-=") &&
       ident && list) {
     const base::StringPiece lhs = ident->value().value();
-    if (lhs == "sources")
+    if (lhs == "sources" || lhs == "deps")
       const_cast<ListNode*>(list)->SortAsStringsList();
   }
 }
@@ -458,7 +458,7 @@ int Printer::Expr(const ParseNode* root,
     CHECK(precedence_.find(binop->op().value()) != precedence_.end());
     AnnotatePreferredMultilineAssignment(binop);
 
-    SortIfSources(binop);
+    SortIfSourcesOrDeps(binop);
 
     Precedence prec = precedence_[binop->op().value()];