Bug 1522288 - Start using microtask for img loading and img decode r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D38717

--HG--
extra : moz-landing-system : lando

dom/base/nsImageLoadingContent.cpp

@@ -43,6 +43,7 @@
 #include "mozAutoDocUpdate.h"
 #include "mozilla/AsyncEventDispatcher.h"
 #include "mozilla/AutoRestore.h"
+#include "mozilla/CycleCollectedJSContext.h"
 #include "mozilla/EventStateManager.h"
 #include "mozilla/EventStates.h"
 #include "mozilla/dom/Element.h"
@@ -352,18 +353,22 @@ already_AddRefed<Promise> nsImageLoadingContent::QueueDecodeAsync(
     return nullptr;
   }
 
-  class QueueDecodeTask final : public Runnable {
+  class QueueDecodeTask final : public MicroTaskRunnable {
    public:
     QueueDecodeTask(nsImageLoadingContent* aOwner, Promise* aPromise,
                     uint32_t aRequestGeneration)
-        : Runnable("nsImageLoadingContent::QueueDecodeTask"),
+        : MicroTaskRunnable(),
           mOwner(aOwner),
           mPromise(aPromise),
           mRequestGeneration(aRequestGeneration) {}
 
-    NS_IMETHOD Run() override {
+    virtual void Run(AutoSlowOperation& aAso) override {
       mOwner->DecodeAsync(std::move(mPromise), mRequestGeneration);
-      return NS_OK;
+    }
+
+    virtual bool Suppressed() override {
+      nsIGlobalObject* global = mOwner->GetOurOwnerDoc()->GetScopeObject();
+      return global && global->IsInSyncOperation();
     }
 
    private:
@@ -378,13 +383,12 @@ already_AddRefed<Promise> nsImageLoadingContent::QueueDecodeAsync(
   }
 
   auto task = MakeRefPtr<QueueDecodeTask>(this, promise, mRequestGeneration);
-  nsContentUtils::RunInStableState(task.forget());
+  CycleCollectedJSContext::Get()->DispatchToMicroTask(task.forget());
   return promise.forget();
 }
 
 void nsImageLoadingContent::DecodeAsync(RefPtr<Promise>&& aPromise,
                                         uint32_t aRequestGeneration) {
-  MOZ_ASSERT(nsContentUtils::IsInStableOrMetaStableState());
   MOZ_ASSERT(aPromise);
   MOZ_ASSERT(mOutstandingDecodePromises > mDecodePromises.Length());
 

dom/html/HTMLImageElement.cpp

@@ -41,6 +41,7 @@
 #include "imgRequestProxy.h"
 
 #include "nsILoadGroup.h"
+#include "mozilla/CycleCollectedJSContext.h"
 
 #include "mozilla/EventDispatcher.h"
 #include "mozilla/EventStates.h"
@@ -75,11 +76,11 @@ namespace dom {
 // Calls LoadSelectedImage on host element unless it has been superseded or
 // canceled -- this is the synchronous section of "update the image data".
 // https://html.spec.whatwg.org/multipage/embedded-content.html#update-the-image-data
-class ImageLoadTask : public Runnable {
+class ImageLoadTask : public MicroTaskRunnable {
  public:
   ImageLoadTask(HTMLImageElement* aElement, bool aAlwaysLoad,
                 bool aUseUrgentStartForChannel)
-      : Runnable("dom::ImageLoadTask"),
+      : MicroTaskRunnable(),
         mElement(aElement),
         mAlwaysLoad(aAlwaysLoad),
         mUseUrgentStartForChannel(aUseUrgentStartForChannel) {
@@ -87,14 +88,18 @@ class ImageLoadTask : public Runnable {
     mDocument->BlockOnload();
   }
 
-  NS_IMETHOD Run() override {
+  virtual void Run(AutoSlowOperation& aAso) override {
     if (mElement->mPendingImageLoadTask == this) {
       mElement->mPendingImageLoadTask = nullptr;
       mElement->mUseUrgentStartForChannel = mUseUrgentStartForChannel;
       mElement->LoadSelectedImage(true, true, mAlwaysLoad);
     }
     mDocument->UnblockOnload(false);
-    return NS_OK;
+  }
+
+  virtual bool Suppressed() override {
+    nsIGlobalObject* global = mElement->GetOwnerGlobal();
+    return global && global->IsInSyncOperation();
   }
 
   bool AlwaysLoad() { return mAlwaysLoad; }
@@ -790,7 +795,7 @@ void HTMLImageElement::QueueImageLoadTask(bool aAlwaysLoad) {
   // The task checks this to determine if it was the last
   // queued event, and so earlier tasks are implicitly canceled.
   mPendingImageLoadTask = task;
-  nsContentUtils::RunInStableState(task.forget());
+  CycleCollectedJSContext::Get()->DispatchToMicroTask(task.forget());
 }
 
 bool HTMLImageElement::HaveSrcsetOrInPicture() {