Revert "Add CHECK()s to investigate Issue 737392"

This reverts commit 95176184.

Reason for revert: Revert code for investigation before going to beta,
as planned.

Original change's description:
> Add CHECK()s to investigate Issue 737392
> 
> ImageResourceContent::content_status_ is suspected to be reset to
> kNotStarted (i.e. 0) during ImageResourceContent::UpdateImage(),
> but therer is no code that sets content_status_ to kNotStarted
> explicitly.
> 
> This CL adds CHECKs() to
> - Check whether |this| is garbage collected unexpectedly during
>   UpdateImage(), and
> - Investigate where |content_status_| becomes kNotStarted precisely.
> 
> This is to be reverted before going to beta.
> 
> Bug: 737392
> Change-Id: I2879bc54771a295a2dd77fed6808c1c08668e262
> Reviewed-on: https://chromium-review.googlesource.com/572036
> Commit-Queue: Hiroshige Hayashizaki <hiroshige@chromium.org>
> Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
> Reviewed-by: Kentaro Hara <haraken@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#486986}

TBR=kinuko@chromium.org,yoav@yoav.ws,haraken@chromium.org,hiroshige@chromium.org,japhet@chromium.org,kouhei@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 737392
Change-Id: Ia13efe886e50873f3ad0c2375ac12819a0cfb46f
Reviewed-on: https://chromium-review.googlesource.com/580427Reviewed-by: Hiroshige Hayashizaki <hiroshige@chromium.org>
Commit-Queue: Hiroshige Hayashizaki <hiroshige@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488468}

third_party/WebKit/Source/core/loader/resource/ImageResourceContent.cpp

@@ -92,12 +92,6 @@ ImageResourceContent* ImageResourceContent::Fetch(FetchParameters& params,
   return resource->GetContent();
 }
 
-ImageResourceContent::~ImageResourceContent() {
-  // For investigation of crbug.com/737392.
-  // TODO(hiroshige): Remove this before going to beta.
-  CHECK(!is_update_image_being_called_);
-}
-
 void ImageResourceContent::SetImageResourceInfo(ImageResourceInfo* info) {
   info_ = info;
 }
@@ -328,18 +322,13 @@ PassRefPtr<Image> ImageResourceContent::CreateImage(bool is_multipart) {
 void ImageResourceContent::ClearImage() {
   if (!image_)
     return;
-  CHECK_NE(GetContentStatus(), ResourceStatus::kNotStarted);
   int64_t length = image_->Data() ? image_->Data()->size() : 0;
-  CHECK_NE(GetContentStatus(), ResourceStatus::kNotStarted);
   v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(-length);
-  CHECK_NE(GetContentStatus(), ResourceStatus::kNotStarted);
 
   // If our Image has an observer, it's always us so we need to clear the back
   // pointer before dropping our reference.
   image_->ClearImageObserver();
-  CHECK_NE(GetContentStatus(), ResourceStatus::kNotStarted);
   image_.Clear();
-  CHECK_NE(GetContentStatus(), ResourceStatus::kNotStarted);
   size_available_ = Image::kSizeUnavailable;
 }
 
@@ -349,8 +338,6 @@ void ImageResourceContent::UpdateToLoadedContentStatus(
   // When |ShouldNotifyFinish|, we set content_status_
   // to a loaded ResourceStatus.
 
-  CHECK_NE(GetContentStatus(), ResourceStatus::kNotStarted);
-
   // Checks |new_status| (i.e. Resource's current status).
   switch (new_status) {
     case ResourceStatus::kCached:
@@ -434,8 +421,10 @@ ImageResourceContent::UpdateImageResult ImageResourceContent::UpdateImage(
     bool is_multipart) {
   TRACE_EVENT0("blink", "ImageResourceContent::updateImage");
 
-  CHECK(!is_update_image_being_called_);
+#if DCHECK_IS_ON()
+  DCHECK(!is_update_image_being_called_);
   AutoReset<bool> scope(&is_update_image_being_called_, true);
+#endif
 
   CHECK_NE(GetContentStatus(), ResourceStatus::kNotStarted);
 
@@ -464,9 +453,7 @@ ImageResourceContent::UpdateImageResult ImageResourceContent::UpdateImage(
         if (!image_)
           image_ = CreateImage(is_multipart);
         DCHECK(image_);
-        CHECK_NE(GetContentStatus(), ResourceStatus::kNotStarted);
         size_available_ = image_->SetData(std::move(data), all_data_received);
-        CHECK_NE(GetContentStatus(), ResourceStatus::kNotStarted);
         DCHECK(all_data_received ||
                size_available_ !=
                    Image::kSizeAvailableAndLoadingAsynchronously);

third_party/WebKit/Source/core/loader/resource/ImageResourceContent.h

@@ -57,8 +57,6 @@ class CORE_EXPORT ImageResourceContent final
 
   static ImageResourceContent* Fetch(FetchParameters&, ResourceFetcher*);
 
-  ~ImageResourceContent() override;
-
   // Returns the nullImage() if the image is not available yet.
   blink::Image* GetImage();
   bool HasImage() const { return image_.Get(); }
@@ -228,7 +226,9 @@ class CORE_EXPORT ImageResourceContent final
   HashCountedSet<ImageResourceObserver*> observers_;
   HashCountedSet<ImageResourceObserver*> finished_observers_;
 
+#if DCHECK_IS_ON()
   bool is_update_image_being_called_ = false;
+#endif
 };
 
 }  // namespace blink