Opt-in stripping of line numbers from console messages of layout tests.

components/test_runner/test_runner.h

Index: components/test_runner/test_runner.h
diff --git a/components/test_runner/test_runner.h b/components/test_runner/test_runner.h
index 69b2ea5fcdd2fc02d2e90a826b188b367354cb98..89bdedae1d2ea70a18cd2917b2fba384fc0c3946 100644
--- a/components/test_runner/test_runner.h
+++ b/components/test_runner/test_runner.h
@@ -131,6 +131,7 @@ class TestRunner : public WebTestRunner {
   bool shouldDumpStatusCallbacks() const;
   bool shouldDumpSpellCheckCallbacks() const;
   bool shouldWaitUntilExternalURLLoad() const;
+  bool shouldDumpConsoleLineNumbers() const;
   const std::set<std::string>* httpHeadersToClear() const;
   bool is_web_platform_tests_mode() const {
     return is_web_platform_tests_mode_;
@@ -454,6 +455,10 @@ class TestRunner : public WebTestRunner {
   // WebFrameClient receives a loadURLExternally() call.
   void WaitUntilExternalURLLoad();
 
+  // Sets a flag that causes line numbers to be stripped from console messages
+  // that are included in the test output.
+  void StripLineNumbersFromConsoleMessages();
+
   // This function sets a flag to dump the drag image when the next drag&drop is
   // initiated. It is equivalent to DumpAsTextWithPixelResults but the pixel
   // results will be the drag image instead of a snapshot of the page.