Remaining changes to build all code in src.git with -Wimplicit-fallthrough.

This CL was uploaded by git cl split.

R=estark@chromium.org

Bug: 177475
Change-Id: Ie191053771d653739fa5bfb5a2a8f143306d2c47
Reviewed-on: https://chromium-review.googlesource.com/891743Reviewed-by: Emily Stark <estark@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532610}

components/security_interstitials/core/ssl_error_ui.cc

@@ -216,6 +216,7 @@ void SSLErrorUI::HandleCommand(SecurityInterstitialCommand command) {
     case CMD_REPORT_PHISHING_ERROR:
       // Not supported by the SSL error page.
       NOTREACHED() << "Unsupported command: " << command;
+      break;
     case CMD_ERROR:
     case CMD_TEXT_FOUND:
     case CMD_TEXT_NOT_FOUND: