Make ApplicationCache a DOMWindowClient

third_party/WebKit/Source/core/loader/appcache/ApplicationCache.cpp

Index: third_party/WebKit/Source/core/loader/appcache/ApplicationCache.cpp
diff --git a/third_party/WebKit/Source/core/loader/appcache/ApplicationCache.cpp b/third_party/WebKit/Source/core/loader/appcache/ApplicationCache.cpp
index 00ac7f1469b1d6d4335810d1867828f0e15e1108..ed4ae6a5d9f5bc8f8826d84bbfed9fef475a6959 100644
--- a/third_party/WebKit/Source/core/loader/appcache/ApplicationCache.cpp
+++ b/third_party/WebKit/Source/core/loader/appcache/ApplicationCache.cpp
@@ -38,8 +38,7 @@
 
 namespace blink {
 
-ApplicationCache::ApplicationCache(LocalFrame* frame)
-    : ContextLifecycleObserver(frame->document()) {
+ApplicationCache::ApplicationCache(LocalFrame* frame) : DOMWindowClient(frame) {
   ApplicationCacheHost* cacheHost = applicationCacheHost();
   if (cacheHost)
     cacheHost->setApplicationCache(this);
@@ -47,12 +46,7 @@ ApplicationCache::ApplicationCache(LocalFrame* frame)
 
 DEFINE_TRACE(ApplicationCache) {
   EventTargetWithInlineData::trace(visitor);
-  ContextLifecycleObserver::trace(visitor);
-}
-
-void ApplicationCache::contextDestroyed() {
-  if (ApplicationCacheHost* cacheHost = applicationCacheHost())

[dcheng, 2017/01/13 09:14:16]

How come it's OK to skip this?

[haraken, 2017/01/13 09:18:21]

cacheHost->setApplicationCache(0) was called just for making
ApplicationCacheHost::dispatchDOMEvent() return early when the context (<-- this
should be window btw) is detached.

After this CL, it is realized by the '!m_domApplicationCache->domWindow()' check
in ApplicationCacheHost::dispatchDOMEvent().

-    cacheHost->setApplicationCache(0);
+  DOMWindowClient::trace(visitor);
 }
 
 ApplicationCacheHost* ApplicationCache::applicationCacheHost() const {
@@ -98,9 +92,7 @@ const AtomicString& ApplicationCache::interfaceName() const {
 }
 
 ExecutionContext* ApplicationCache::getExecutionContext() const {
-  if (frame())
-    return frame()->document();
-  return 0;
+  return frame() ? frame()->document() : nullptr;
 }
 
 const AtomicString& ApplicationCache::toEventType(