Add a Certificate Viewer link to the Page Info dropdown

In Chrome 55, we removed the easy path from Page Info to the
Certificate Viewer dialog. This change puts it back in a new
Certificate view just above the Cookie view.

BUG=663971

Review-Url: https://codereview.chromium.org/2846913002
Cr-Commit-Position: refs/heads/master@{#468539}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index a979408c5..0958224 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -2773,6 +2773,12 @@
      flag_descriptions::kEnableHeapProfilingDescription, kOsAll,
      MULTI_VALUE_TYPE(kEnableHeapProfilingChoices)},
 
+#if defined(TOOLKIT_VIEWS) || (defined(OS_MACOSX) && !defined(OS_IOS))
+    {"show-cert-link", flag_descriptions::kShowCertLinkOnPageInfoName,
+     flag_descriptions::kShowCertLinkOnPageInfoDescription, kOsDesktop,
+     SINGLE_VALUE_TYPE(switches::kShowCertLink)},
+#endif
+
     // NOTE: Adding new command-line switches requires adding corresponding
     // entries to enum "LoginCustomFlags" in histograms.xml. See note in
     // histograms.xml and don't forget to run AboutFlagsHistogramTest unit test.