Add certificate error handling to devtools.

content/public/browser/web_contents_observer.cc

Index: content/public/browser/web_contents_observer.cc
diff --git a/content/public/browser/web_contents_observer.cc b/content/public/browser/web_contents_observer.cc
index 01d158d38d1bfb428b1a855ef5ee344affa18000..19d4e75c1fa9e50fa6ff27a2f3de9fd4d94716d7 100644
--- a/content/public/browser/web_contents_observer.cc
+++ b/content/public/browser/web_contents_observer.cc
@@ -72,4 +72,10 @@ void WebContentsObserver::ResetWebContents() {
   web_contents_ = nullptr;
 }
 
+bool WebContentsObserver::NotifyCertificateError(int cert_error,
+                                                 const GURL& request_url,
+                                                 CertErrorCallback callback) {
+  return false;
+}
+
 }  // namespace content