Implement updateViaCache flag and no-cache by default for main service worker scripts

third_party/WebKit/Source/core/html/HTMLLinkElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLLinkElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLLinkElement.cpp b/third_party/WebKit/Source/core/html/HTMLLinkElement.cpp
index d7c296d5ff41a0f409326dc1c4d7b1729f323c9b..20994908b8bc876374d81b8b76daa54784936cd0 100644
--- a/third_party/WebKit/Source/core/html/HTMLLinkElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLLinkElement.cpp
@@ -45,6 +45,19 @@
 
 namespace blink {
 
+namespace {
+WebServiceWorkerUpdateViaCache ParseUpdateViaCache(const AtomicString& value) {
+  if (value == "imports")
+    return WebServiceWorkerUpdateViaCache::kImports;
+  if (value == "all")
+    return WebServiceWorkerUpdateViaCache::kAll;
+  if (value == "none")
+    return WebServiceWorkerUpdateViaCache::kNone;
+  // Default value
+  return WebServiceWorkerUpdateViaCache::kImports;
+}
+}  // namespace
+
 using namespace HTMLNames;
 
 inline HTMLLinkElement::HTMLLinkElement(Document& document,
@@ -102,6 +115,9 @@ void HTMLLinkElement::ParseAttribute(
   } else if (name == scopeAttr) {
     scope_ = value;
     Process();
+  } else if (name == updateviacacheAttr) {
+    update_via_cache_ = ParseUpdateViaCache(value);
+    Process();
   } else if (name == disabledAttr) {
     UseCounter::Count(GetDocument(), WebFeature::kHTMLLinkElementDisabled);
     if (LinkStyle* link = GetLinkStyle())