Explicitly track the lifecycle of PendingScript.

third_party/WebKit/Source/core/dom/PendingScript.cpp

Index: third_party/WebKit/Source/core/dom/PendingScript.cpp
diff --git a/third_party/WebKit/Source/core/dom/PendingScript.cpp b/third_party/WebKit/Source/core/dom/PendingScript.cpp
index c3471192149d5137d2587196893412edf0d0d8b1..e5e7341e991f9768b1f6cf59e9a5d6a2843dde1a 100644
--- a/third_party/WebKit/Source/core/dom/PendingScript.cpp
+++ b/third_party/WebKit/Source/core/dom/PendingScript.cpp
@@ -57,7 +57,7 @@ PendingScript::PendingScript(ScriptElementBase* element,
                              ScriptResource* resource,
                              const TextPosition& starting_position,
                              bool is_for_testing)
-    : watching_for_load_(false),
+    : ready_state_(resource ? kWaitingForResource : kReady),
       element_(element),
       starting_position_(starting_position),
       integrity_failure_(false),
@@ -80,8 +80,7 @@ NOINLINE void PendingScript::CheckState() const {
 
 void PendingScript::Dispose() {
   StopWatchingForLoad();
-  DCHECK(!client_);
-  DCHECK(!watching_for_load_);
+  DCHECK(!WatchingForLoad());
 
   MemoryCoordinator::Instance().UnregisterClient(this);
   SetResource(nullptr);
@@ -97,25 +96,24 @@ void PendingScript::Dispose() {
 void PendingScript::WatchForLoad(PendingScriptClient* client) {
   CheckState();
 
-  DCHECK(!watching_for_load_);
+  DCHECK(!WatchingForLoad());
+  DCHECK(client);
   // addClient() will call streamingFinished() if the load is complete. Callers
   // who do not expect to be re-entered from this call should not call
   // watchForLoad for a PendingScript which isReady. We also need to set
   // m_watchingForLoad early, since addClient() can result in calling
   // notifyFinished and further stopWatchingForLoad().
-  watching_for_load_ = true;
   client_ = client;
   if (IsReady())
     client_->PendingScriptFinished(this);
 }
 
 void PendingScript::StopWatchingForLoad() {
-  if (!watching_for_load_)
+  if (!WatchingForLoad())
     return;
   CheckState();
   DCHECK(GetResource());
   client_ = nullptr;
-  watching_for_load_ = false;
 }
 
 ScriptElementBase* PendingScript::GetElement() const {
@@ -129,8 +127,9 @@ ScriptElementBase* PendingScript::GetElement() const {
 void PendingScript::StreamingFinished() {
   CheckState();
   DCHECK(GetResource());

[hiroshige, 2017/04/24 19:16:53]

DCHECK_EQ(ready_state_, kWaitingForStreaming);

[jbroman, 2017/05/01 15:08:01]

Done.

-  if (client_)
-    client_->PendingScriptFinished(this);
+
+  bool error_occurred = GetResource()->ErrorOccurred() || integrity_failure_;
+  AdvanceReadyState(error_occurred ? kErrorOccurred : kReady);
 }
 
 void PendingScript::MarkParserBlockingLoadStartTime() {
@@ -184,6 +183,8 @@ static bool CheckScriptResourceIntegrity(Resource* resource,
 }
 
 void PendingScript::NotifyFinished(Resource* resource) {
+  DCHECK_EQ(ready_state_, kWaitingForResource);
+
   // The following SRI checks need to be here because, unfortunately, fetches
   // are not done purely according to the Fetch spec. In particular,
   // different requests for the same resource do not have different
@@ -211,12 +212,13 @@ void PendingScript::NotifyFinished(Resource* resource) {
     integrity_failure_ = !CheckScriptResourceIntegrity(resource, element_);
   }
 
-  // If script streaming is in use, the client will be notified in
-  // streamingFinished.
+  // We are now waiting for script streaming to finish.
+  // If there is no script streamer, this step completes immediately.
+  AdvanceReadyState(kWaitingForStreaming);
   if (streamer_)
     streamer_->NotifyFinished(resource);
-  else if (client_)
-    client_->PendingScriptFinished(this);
+  else
+    StreamingFinished();
 }
 
 void PendingScript::NotifyAppendData(ScriptResource* resource) {
@@ -235,8 +237,9 @@ DEFINE_TRACE(PendingScript) {
 ClassicScript* PendingScript::GetSource(const KURL& document_url,
                                         bool& error_occurred) const {
   CheckState();
+  DCHECK(IsReady());
 
-  error_occurred = this->ErrorOccurred();
+  error_occurred = ErrorOccurred();
   if (GetResource()) {
     DCHECK(GetResource()->IsLoaded());
     if (streamer_ && !streamer_->StreamingSuppressed())
@@ -250,28 +253,13 @@ ClassicScript* PendingScript::GetSource(const KURL& document_url,
 
 void PendingScript::SetStreamer(ScriptStreamer* streamer) {
   DCHECK(!streamer_);
-  DCHECK(!watching_for_load_);
+  DCHECK(!WatchingForLoad());
+  DCHECK(!streamer->IsFinished());
+  DCHECK_LT(ready_state_, kWaitingForStreaming);
   streamer_ = streamer;
   CheckState();
 }
 
-bool PendingScript::IsReady() const {
-  CheckState();
-  if (GetResource()) {
-    return GetResource()->IsLoaded() && (!streamer_ || streamer_->IsFinished());
-  }
-
-  return true;
-}
-
-bool PendingScript::ErrorOccurred() const {
-  CheckState();
-  if (GetResource())
-    return GetResource()->ErrorOccurred() || integrity_failure_;
-
-  return false;
-}
-
 void PendingScript::OnPurgeMemory() {
   CheckState();
   if (!streamer_)
@@ -295,4 +283,17 @@ void PendingScript::StartStreamingIfPossible(
       TaskRunnerHelper::Get(TaskType::kNetworking, document));
 }
 
+void PendingScript::AdvanceReadyState(ReadyState ready_state) {
+  // The ready state should monotonically advance.
+  DCHECK_GT(ready_state, ready_state_);
+
+  // The state should not advance from one completed state to another.
+  if (ready_state >= kReady)
+    DCHECK_LT(ready_state_, kReady);
+
+  ready_state_ = ready_state;
+  if (ready_state >= kReady && client_)
+    client_->PendingScriptFinished(this);
+}
+
 }  // namespace blink