Add testRunner.insertStyleSheet for testing style sheet injection.

content/shell/renderer/test_runner/test_runner.h

Index: content/shell/renderer/test_runner/test_runner.h
diff --git a/content/shell/renderer/test_runner/test_runner.h b/content/shell/renderer/test_runner/test_runner.h
index ef26e200a74b67e7908fc876d1aa857657dd875e..57047c679cf1f6488d363364db4798a92130e88d 100644
--- a/content/shell/renderer/test_runner/test_runner.h
+++ b/content/shell/renderer/test_runner/test_runner.h
@@ -244,8 +244,13 @@ class TestRunner : public WebTestRunner,
   void ForceRedSelectionColors();
 
   // Adds a style sheet to be injected into new documents.
+  // TODO(dcheng): This will be removed in a followup patch.
   void InjectStyleSheet(const std::string& source_code, bool all_frames);
 
+  // Add |source_code| as an injected stylesheet to the active document of the
+  // window of the current V8 context.
+  void InsertStyleSheet(const std::string& source_code);
+
   bool FindString(const std::string& search_text,
                   const std::vector<std::string>& options_array);