cc: Fix PaintImage deserialization using TransferCache.

If we have a valid transfer cache entry but it doesn't exist in the
cache, we proceed with using an empty image. Since any referenced
entries must be serialized and locked with each command, it should be
considered an error.

R=ericrk@chromium.org

Bug: 853491
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I328d441163aa290693efd4870aeb3717c1586163
Reviewed-on: https://chromium-review.googlesource.com/1108556Reviewed-by: Eric Karl <ericrk@chromium.org>
Commit-Queue: Khushal <khushalsagar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569490}

cc/paint/paint_op_reader.cc

@@ -315,6 +315,10 @@ void PaintOpReader::Read(PaintImage* image) {
                  .set_id(PaintImage::GetNextId())
                  .set_image(entry->image(), PaintImage::kNonLazyStableId)
                  .TakePaintImage();
+  } else {
+    // If a transfer cache id exists, we must have a valid entry for it in the
+    // cache.
+    SetInvalid();
   }
 }