tools/gn: rename char_offset to column_number

tools/gn/location.h

Index: tools/gn/location.h
diff --git a/tools/gn/location.h b/tools/gn/location.h
index b56e73de777837deeaea6ede3b665d62d26cddb9..44d1a6fe68f614112bf1d57993cc8af8bb92755c 100644
--- a/tools/gn/location.h
+++ b/tools/gn/location.h
@@ -13,11 +13,11 @@ class InputFile;
 class Location {
  public:
   Location();
-  Location(const InputFile* file, int line_number, int char_offset, int byte);
+  Location(const InputFile* file, int line_number, int column_number, int byte);
 
   const InputFile* file() const { return file_; }
   int line_number() const { return line_number_; }
-  int char_offset() const { return char_offset_; }
+  int column_number() const { return column_number_; }
   int byte() const { return byte_; }
 
   bool operator==(const Location& other) const;
@@ -27,12 +27,12 @@ class Location {
   // Returns a string with the file, line, and (optionally) the character
   // offset for this location. If this location is null, returns an empty
   // string.
-  std::string Describe(bool include_char_offset) const;
+  std::string Describe(bool include_column_number) const;
 
  private:
   const InputFile* file_;  // Null when unset.
   int line_number_;        // -1 when unset. 1-based.
-  int char_offset_;        // -1 when unset. 1-based.
+  int column_number_;      // -1 when unset. 1-based.
   int byte_;               // Index into the buffer, 0-based.
 };