Work on getting things built with -Wimplicit-fallthrough. This CL was uploaded by git cl split.

Bug: 177475
R=meacer@chromium.org

Change-Id: Iaa60724d160144a2aa74c49dca0be44229f29ccd
Reviewed-on: https://chromium-review.googlesource.com/889818Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532105}

components/security_interstitials/core/bad_clock_ui.cc

@@ -118,6 +118,7 @@ void BadClockUI::HandleCommand(SecurityInterstitialCommand command) {
     case CMD_REPORT_PHISHING_ERROR:
       // Not supported by the bad clock error page.
       NOTREACHED() << "Unsupported command: " << command;
+      break;
     case CMD_ERROR:
     case CMD_TEXT_FOUND:
     case CMD_TEXT_NOT_FOUND:

components/security_interstitials/core/mitm_software_ui.cc

@@ -96,6 +96,7 @@ void MITMSoftwareUI::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:

components/security_interstitials/core/safe_browsing_loud_error_ui.cc

@@ -119,8 +119,9 @@ void SafeBrowsingLoudErrorUI::HandleCommand(
         controller()->Proceed();
         break;
       }
+      // If the user can't proceed, fall through to CMD_DONT_PROCEED.
+      FALLTHROUGH;
     }
-    // If the user can't proceed, fall through to CMD_DONT_PROCEED.
     case CMD_DONT_PROCEED: {
       // User pressed on the button to return to safety.
       // Don't record the user action here because there are other ways of