Bug 1892643. Allow checking for shutdown in the image decode pool after the decode pool has been cleared. r=gfx-reviewers,nical

Differential Revision: https://phabricator.services.mozilla.com/D208086

image/AnimationSurfaceProvider.cpp

@@ -245,8 +245,7 @@ void AnimationSurfaceProvider::Run() {
       // release the thread as soon as possible. The animation may advance even
       // during shutdown, which keeps us decoding, and thus blocking the decode
       // pool during teardown.
-      if (!mDecoder || !continueDecoding ||
-          DecodePool::Singleton()->IsShuttingDown()) {
+      if (!mDecoder || !continueDecoding || DecodePool::IsShuttingDown()) {
         return;
       }
 
@@ -282,8 +281,7 @@ void AnimationSurfaceProvider::Run() {
     // animation may advance even during shutdown, which keeps us decoding, and
     // thus blocking the decode pool during teardown.
     MOZ_ASSERT(result == LexerResult(Yield::OUTPUT_AVAILABLE));
-    if (!checkForNewFrameAtYieldResult ||
-        DecodePool::Singleton()->IsShuttingDown()) {
+    if (!checkForNewFrameAtYieldResult || DecodePool::IsShuttingDown()) {
       return;
     }
   }

image/DecodePool.cpp

@@ -16,6 +16,7 @@
 #include "mozilla/StaticPrefs_image.h"
 #include "mozilla/TaskController.h"
 #include "mozilla/TimeStamp.h"
+#include "mozilla/AppShutdown.h"
 #include "nsCOMPtr.h"
 #include "nsIObserverService.h"
 #include "nsThreadManager.h"
@@ -132,7 +133,13 @@ DecodePool::Observe(nsISupports*, const char* aTopic, const char16_t*) {
   return NS_OK;
 }
 
-bool DecodePool::IsShuttingDown() const { return mShuttingDown; }
+/* static */ bool DecodePool::IsShuttingDown() {
+  if (MOZ_UNLIKELY(!sSingleton)) {
+    return AppShutdown::IsInOrBeyond(ShutdownPhase::XPCOMShutdownThreads);
+  }
+
+  return sSingleton->mShuttingDown;
+}
 
 class DecodingTask final : public Task {
  public:

image/DecodePool.h

@@ -56,7 +56,7 @@ class DecodePool final : public nsIObserver {
 
   /// True if the DecodePool is being shutdown. This may only be called by
   /// threads from the pool to check if they should keep working or not.
-  bool IsShuttingDown() const;
+  static bool IsShuttingDown();
 
   /// Ask the DecodePool to run @aTask asynchronously and return immediately.
   void AsyncRun(IDecodingTask* aTask);