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

Bug: 177475
R=rsleevi@chromium.org

Change-Id: I887321c9251529a6377eefa32fe3bb87638eb845
Reviewed-on: https://chromium-review.googlesource.com/889800Reviewed-by: Ryan Sleevi <rsleevi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532116}

components/certificate_transparency/single_tree_tracker.cc

@@ -515,7 +515,8 @@ void SingleTreeTracker::OnMemoryPressure(
       break;
     case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_CRITICAL:
       pending_entries_.clear();
-    // Fall through to clearing the other cache.
+      // Fall through to clearing the other cache.
+      FALLTHROUGH;
     case base::MemoryPressureListener::MEMORY_PRESSURE_LEVEL_MODERATE:
       checked_entries_.Clear();
       break;