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

Bug: 177475
R=mkwst@chromium.org

Change-Id: I1494c1b0bdacea56c741bb0ec2734cff0d5e94ba
Reviewed-on: https://chromium-review.googlesource.com/889758Reviewed-by: Mike West <mkwst@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532841}

third_party/WebKit/Source/platform/loader/fetch/ResourceFetcher.cpp

@@ -120,6 +120,7 @@ ResourceLoadPriority TypeToPriority(Resource::Type type) {
       return ResourceLoadPriority::kVeryHigh;
     case Resource::kXSLStyleSheet:
       DCHECK(RuntimeEnabledFeatures::XSLTEnabled());
+      FALLTHROUGH;
     case Resource::kRaw:
     case Resource::kImportResource:
     case Resource::kScript:
@@ -244,6 +245,7 @@ WebURLRequest::RequestContext ResourceFetcher::DetermineRequestContext(
       return WebURLRequest::kRequestContextHyperlink;
     case Resource::kXSLStyleSheet:
       DCHECK(RuntimeEnabledFeatures::XSLTEnabled());
+      FALLTHROUGH;
     case Resource::kCSSStyleSheet:
       return WebURLRequest::kRequestContextStyle;
     case Resource::kScript:
@@ -757,7 +759,7 @@ Resource* ResourceFetcher::RequestResourceInternal(
   switch (policy) {
     case kReload:
       GetMemoryCache()->Remove(resource);
-    // Fall through
+      FALLTHROUGH;
     case kLoad:
       resource = CreateResourceForLoading(params, factory);
       break;