Minor fixes to tools/gn.

tools/gn/substitution_writer.cc

 // Copyright 2014 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.
 
 #include "tools/gn/substitution_writer.h"
 
 #include "tools/gn/build_settings.h"
 #include "tools/gn/escape.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/output_file.h"
@@ skipping 51 matching lines @@
     "      \"args\" variable.\n"
     "        \"//foo/bar/baz.txt\" => \"../../foo/bar/baz.txt\"\n"
     "\n"
     "  {{source_file_part}}\n"
     "      The file part of the source including the extension.\n"
     "        \"//foo/bar/baz.txt\" => \"baz.txt\"\n"
     "\n"
     "  {{source_name_part}}\n"
     "      The filename part of the source file with no directory or\n"
     "      extension. This will generally be used for specifying a\n"
-    "      transformation from a soruce file to a destination file with the\n"
+    "      transformation from a source file to a destination file with the\n"
     "      same name but different extension.\n"
     "        \"//foo/bar/baz.txt\" => \"baz\"\n"
     "\n"
     "  {{source_dir}}\n"
     "      The directory (*) containing the source file with no\n"
     "      trailing slash.\n"
     "        \"//foo/bar/baz.txt\" => \"../../foo/bar\"\n"
     "\n"
     "  {{source_root_relative_dir}}\n"
     "      The path to the source file's directory relative to the source\n"
@@ skipping 84 matching lines @@
     out << result;
 }
 
 // static
 void SubstitutionWriter::GetListAsSourceFiles(
     const SubstitutionList& list,
     std::vector<SourceFile>* output) {
   for (const auto& pattern : list.list()) {
     CHECK(pattern.ranges().size() == 1 &&
           pattern.ranges()[0].type == SUBSTITUTION_LITERAL)
-        << "The substitution patterm \""
+        << "The substitution pattern \""
         << pattern.AsString()
         << "\" was expected to be a literal with no {{substitutions}}.";
     const std::string& literal = pattern.ranges()[0].literal;
     CHECK(literal.size() >= 1 && literal[0] == '/')
         << "The result of the pattern \""
         << pattern.AsString()
         << "\" was not an absolute path.";
     output->push_back(SourceFile(literal));
   }
 }
@@ skipping 364 matching lines @@
       // does not include the dot but the tool's does.
       if (target->output_extension().empty())
         return tool->default_output_extension();
       return std::string(".") + target->output_extension();
 
     default:
       NOTREACHED();
       return std::string();
   }
 }