tools/gn: rename char_offset to column_number

tools/gn/parse_tree.cc

Index: tools/gn/parse_tree.cc
diff --git a/tools/gn/parse_tree.cc b/tools/gn/parse_tree.cc
index 38133dd8ae056e9c78308d0defe352cfe13fb24b..93711aed84e4d618664a16bb7a2578576de18f44 100644
--- a/tools/gn/parse_tree.cc
+++ b/tools/gn/parse_tree.cc
@@ -253,7 +253,7 @@ Value AccessorNode::ExecuteScopeAccess(Scope* scope, Err* err) const {
 void AccessorNode::SetNewLocation(int line_number) {
   Location old = base_.location();
   base_.set_location(
-      Location(old.file(), line_number, old.char_offset(), old.byte()));
+      Location(old.file(), line_number, old.column_number(), old.byte()));
 }
 
 // BinaryOpNode ---------------------------------------------------------------
@@ -480,7 +480,7 @@ void IdentifierNode::Print(std::ostream& out, int indent) const {
 void IdentifierNode::SetNewLocation(int line_number) {
   Location old = value_.location();
   value_.set_location(
-      Location(old.file(), line_number, old.char_offset(), old.byte()));
+      Location(old.file(), line_number, old.column_number(), old.byte()));
 }
 
 // ListNode -------------------------------------------------------------------
@@ -739,7 +739,7 @@ void LiteralNode::Print(std::ostream& out, int indent) const {
 void LiteralNode::SetNewLocation(int line_number) {
   Location old = value_.location();
   value_.set_location(
-      Location(old.file(), line_number, old.char_offset(), old.byte()));
+      Location(old.file(), line_number, old.column_number(), old.byte()));
 }
 
 // UnaryOpNode ----------------------------------------------------------------