Revise layout tests to avoid race condition

Revise layout tests to avoid race condition

At this moment, there is a race condition in this layout tests. This
layout tests includes the following steps:
1). Send a blob to worker
2). Right after that, both worker and main start creating ImageBitmap
    from the blob.
3). Worker send the created ImageBitmap to main.
4). Get a Image from the blob using URL.createObjectURL(blob), Once this
    Image is loaded, compare this Image with the ImageBitmaps created
    in main and worker, they should have the same pixel data.

Now the problem here is that the main thread could wait for the Image to
be loaded and while in the meantime still wait for the created ImageBitmap
from worker. And there is a race condition here because one of them could
happen first and there is no guarantee to that.

This CL make changes such that the Image onload returns a promise. Also,
worker returning the ImageBitmap also returns a promise. We compare
the pixel data only when both promises are resolved. In this case, there
will be no race condition.

BUG=594196
Committed: https://crrev.com/6590bde0345a7d38a603cb4839ad2afd088db024
Cr-Commit-Position: refs/heads/master@{#380992}

[xidachen, 2016-03-12 02:09:32]

xidachen@chromium.org changed reviewers:
+ jbroman@chromium.org

[xidachen, 2016-03-12 02:09:32]

PTAL.

[jbroman, 2016-03-14 14:58:42]

lgtm

https://codereview.chromium.org/1792623002/diff/1/third_party/WebKit/LayoutTe...
File
third_party/WebKit/LayoutTests/virtual/threaded/fast/canvas-toBlob/canvas-createImageBitmap-blob-in-workers.html
(right):

https://codereview.chromium.org/1792623002/diff/1/third_party/WebKit/LayoutTe...
third_party/WebKit/LayoutTests/virtual/threaded/fast/canvas-toBlob/canvas-createImageBitmap-blob-in-workers.html:45:
var newImg = new Image();
nit: Not new to this CL, but I'm a little confused about what this test is
testing. The description suggest it's racing use of createImageBitmap on workers
and in the main context, but it's not obvious to me what the <img> has to do
with it. Would be nice to have a comment explaining what we gain by adding this
extra step.

https://codereview.chromium.org/1792623002/diff/1/third_party/WebKit/LayoutTe...
third_party/WebKit/LayoutTests/virtual/threaded/fast/canvas-toBlob/canvas-createImageBitmap-blob-in-workers.html:65:
}
super-nit: semicolon on this line?

https://codereview.chromium.org/1792623002/diff/1/third_party/WebKit/LayoutTe...
third_party/WebKit/LayoutTests/virtual/threaded/fast/canvas-toBlob/canvas-createImageBitmap-blob-in-workers.html:68:
Promise.all([imageLoaded, getMessageFromWorker]).then(([imageData2,
newImageBitmap]) => {
nit: The names "imageData" and "imageData2" make it a little hard to remember
which is from where.

WDYT of something like imageData2 -> "imageDataFromImg", "newImageBitmap" ->
"imageBitmapFromWorker"?

[xidachen, 2016-03-14 15:15:54]

The CQ bit was checked by xidachen@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-03-14 15:16:03]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1792623002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1792623002/20001

[commit-bot: I haz the power, 2016-03-14 16:09:31]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-03-14 16:09:32]

Dry run: This issue passed the CQ dry run.

[xidachen, 2016-03-14 16:49:00]

The CQ bit was checked by xidachen@chromium.org

[xidachen, 2016-03-14 16:49:00]

The patchset sent to the CQ was uploaded after l-g-t-m from jbroman@chromium.org
Link to the patchset: https://codereview.chromium.org/1792623002/#ps20001
(title: "nits")

[commit-bot: I haz the power, 2016-03-14 16:49:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1792623002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1792623002/20001

[commit-bot: I haz the power, 2016-03-14 16:58:13]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-03-14 16:59:26]

Description was changed from

==========
Revise layout tests to avoid race condition

At this moment, there is a race condition in this layout tests. This
layout tests includes the following steps:
1). Send a blob to worker
2). Right after that, both worker and main start creating ImageBitmap
    from the blob.
3). Worker send the created ImageBitmap to main.
4). Get a Image from the blob using URL.createObjectURL(blob), Once this
    Image is loaded, compare this Image with the ImageBitmaps created
    in main and worker, they should have the same pixel data.

Now the problem here is that the main thread could wait for the Image to
be loaded and while in the meantime still wait for the created ImageBitmap
from worker. And there is a race condition here because one of them could
happen first and there is no guarantee to that.

This CL make changes such that the Image onload returns a promise. Also,
worker returning the ImageBitmap also returns a promise. We compare
the pixel data only when both promises are resolved. In this case, there
will be no race condition.

BUG=594196
==========

to

==========
Revise layout tests to avoid race condition

At this moment, there is a race condition in this layout tests. This
layout tests includes the following steps:
1). Send a blob to worker
2). Right after that, both worker and main start creating ImageBitmap
    from the blob.
3). Worker send the created ImageBitmap to main.
4). Get a Image from the blob using URL.createObjectURL(blob), Once this
    Image is loaded, compare this Image with the ImageBitmaps created
    in main and worker, they should have the same pixel data.

Now the problem here is that the main thread could wait for the Image to
be loaded and while in the meantime still wait for the created ImageBitmap
from worker. And there is a race condition here because one of them could
happen first and there is no guarantee to that.

This CL make changes such that the Image onload returns a promise. Also,
worker returning the ImageBitmap also returns a promise. We compare
the pixel data only when both promises are resolved. In this case, there
will be no race condition.

BUG=594196

Committed: https://crrev.com/6590bde0345a7d38a603cb4839ad2afd088db024
Cr-Commit-Position: refs/heads/master@{#380992}
==========

[commit-bot: I haz the power, 2016-03-14 16:59:27]

Patchset 2 (id:??) landed as
https://crrev.com/6590bde0345a7d38a603cb4839ad2afd088db024
Cr-Commit-Position: refs/heads/master@{#380992}