cc: Don't allocate 0-size discardable memory.

This patch ensures that when processing images we don't try to allocate
0 bytes of discardable memory. For now, allocate 1 byte with a TODO
to skip these images altogether.

R=enne
BUG=579498
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1633933002

Cr-Commit-Position: refs/heads/master@{#371413}

cc/tiles/image_decode_controller.cc

@@ -318,8 +318,12 @@ ImageDecodeController::DecodeImageInternal(const ImageKey& key,
                           decoded_info.minRowBytes());
 
   // Now scale the pixels into the destination size.
-  SkImageInfo scaled_info = SkImageInfo::MakeN32Premul(
-      key.target_size().width(), key.target_size().height());
+  // TODO(vmpstr): Once we support skipping images altogether, we can remove
+  // this and skip drawing images that are empty in size. crbug.com/581163
+  const gfx::Size& target_size =
+      key.target_size().IsEmpty() ? gfx::Size(1, 1) : key.target_size();
+  SkImageInfo scaled_info =
+      SkImageInfo::MakeN32Premul(target_size.width(), target_size.height());
   scoped_ptr<base::DiscardableMemory> scaled_pixels;
   {
     TRACE_EVENT0(