Only update ImageBitmap if we have a real image

ImageBitmap can fail to be created, if it doesn't fit in memory.

Bug: 936885
Change-Id: I694ed4fb964782f84cdec33d465a1e404aca6324
Reviewed-on: https://chromium-review.googlesource.com/c/1496921
Commit-Queue: Fernando Serboncini <fserb@chromium.org>
Reviewed-by: Mohammad Reza Zakerinasab <zakerinasab@chromium.org>
Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636848}

third_party/blink/renderer/core/imagebitmap/image_bitmap.cc

@@ -824,11 +824,16 @@ void ImageBitmap::UpdateImageBitmapMemoryUsage() {
   // but this is breaking some tests due to the repaint of the image.
   int bytes_per_pixel = 4;
 
-  base::CheckedNumeric<int32_t> memory_usage_checked = bytes_per_pixel;
-  memory_usage_checked *= image_->width();
-  memory_usage_checked *= image_->height();
-  int32_t new_memory_usage =
-      memory_usage_checked.ValueOrDefault(std::numeric_limits<int32_t>::max());
+  int32_t new_memory_usage = 0;
+
+  if (image_) {
+    base::CheckedNumeric<int32_t> memory_usage_checked = bytes_per_pixel;
+    memory_usage_checked *= image_->width();
+    memory_usage_checked *= image_->height();
+    new_memory_usage = memory_usage_checked.ValueOrDefault(
+        std::numeric_limits<int32_t>::max());
+  }
+
   v8::Isolate::GetCurrent()->AdjustAmountOfExternalAllocatedMemory(
       new_memory_usage - memory_usage_);
   memory_usage_ = new_memory_usage;