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

This CL was uploaded by git cl split.

R=agl@chromium.org

Bug: 177475
Change-Id: I222339d1ce16c92c54e3ad7ddbdd8b4e9cc92b5e
Reviewed-on: https://chromium-review.googlesource.com/891920Reviewed-by: Adam Langley <agl@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532608}

chrome/browser/ssl/ssl_error_handler.cc

@@ -880,6 +880,7 @@ void SSLErrorHandler::ShowDynamicInterstitial(
   switch (dynamic_interstitial.interstitial_type) {
     case chrome_browser_ssl::DynamicInterstitial::INTERSTITIAL_PAGE_NONE:
       NOTREACHED();
+      return;
     case chrome_browser_ssl::DynamicInterstitial::INTERSTITIAL_PAGE_SSL:
       delegate_->ShowSSLInterstitial(dynamic_interstitial.support_url);
       return;