Fixing all the cases that an image received can be null

We want to ensure that the ImageLayerBridge will not try and dereference
a potential null skImage. Adding a check to assume it was a nullptr, even
if the StaticBitmapImage was not null but pointed internally to a null.
skImage.

Changing how the white skbitmap is generated inside webgl to be more
robust against a potential context loss.

Bug: 996287
Change-Id: I2c65a34faab9f26042c1f4ccb3eca23788955dbe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1784983
Commit-Queue: Juanmi Huertas <juanmihd@chromium.org>
Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#694331}

third_party/blink/renderer/platform/graphics/gpu/drawing_buffer.cc

@@ -557,9 +557,10 @@ scoped_refptr<StaticBitmapImage> DrawingBuffer::TransferToStaticBitmapImage(
     // to transferToImageBitmap are made back-to-back, or when the context gets
     // lost. We intentionally leave the transparent black image in legacy color
     // space.
-    sk_sp<SkSurface> surface =
-        SkSurface::MakeRasterN32Premul(size_.Width(), size_.Height());
-    return StaticBitmapImage::Create(surface->makeImageSnapshot());
+    SkBitmap black_bitmap;
+    black_bitmap.allocN32Pixels(size_.Width(), size_.Height());
+    black_bitmap.eraseARGB(0, 255, 255, 255);
+    return StaticBitmapImage::Create(SkImage::MakeFromBitmap(black_bitmap));
   }
 
   DCHECK_EQ(size_.Width(), transferable_resource.size.width());

third_party/blink/renderer/platform/graphics/gpu/image_layer_bridge.cc

@@ -46,6 +46,11 @@ ImageLayerBridge::~ImageLayerBridge() {
 void ImageLayerBridge::SetImage(scoped_refptr<StaticBitmapImage> image) {
   if (disposed_)
     return;
+  // There could be the case that the current SkImage (encapsulated in the image
+  // parameter of the function) is null, that means that something went wrong
+  // during the creation of the image and we should not try and setImage with it
+  if (image_ && !image_->PaintImageForCurrentFrame().GetSkImage())
+    return;
 
   image_ = std::move(image);
   if (image_) {