Remove EventSender from ImageLoader

Remove EventSender from ImageLoader

Instead of using EventSender, this CL schedules ImageLoader's
load and error events using PostCancellableTask.
has_pending_load_event_ and has_pending_error_event_ booleans are
replaced with TaskHandle to the cancellable tasks and IsActive() calls.

This CL removes the dependencies between Document's load event and
<img> load events via EventSender.

This CL removes EventSender.h as ImageLoader was the last user of that.

Test changes:
stop-loading.html:
  testharness.js waits for the window load event before finishing.
  Previously, we call window.stop() in <img> load event, but window
  load event is fired, because the <img> load event is fired from
  Document::ImplicitClose() via EventSender. At that time window.stop()
  doesn't stop the window load event.
  After this CL, <img> load event is fired separately from
  Document::ImplicitClose(), and thus window.stop() stops the window
  load event.
  To work around this, this CL triggers window load event explicitly
  just to signal testharness.js to finish.

http/tests/loading/preload-image-sizes-2x.html and
http/tests/loading/preload-picture-sizes-2x.html:
  The tests uses srcset-helper.js that reloads the page with empty
  cache in the window load event.
  Because this CL changes the timing of the window load event, this
  causes some asynchronous tasks that cause new image loading to be
  scheduled before window load event and executed after that, causing
  some images left on the cache before reloading starts.
  This CL works around the issue by waiting a little bit for those
  tasks to be executed, and then clearing the cache and reloading the
  page.

BUG=624697, 720268
Review-Url: https://codereview.chromium.org/2863763003
Cr-Commit-Position: refs/heads/master@{#474086}
Committed: https://chromium.googlesource.com/chromium/src/+/da70e32d811fffe4e15728ba858dbdfa3180ed59

[hiroshige, 2017-05-05 01:05:00]

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

[commit-bot: I haz the power, 2017-05-05 01:05:26]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[hiroshige, 2017-05-05 01:13:50]

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

[commit-bot: I haz the power, 2017-05-05 01:14:29]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[hiroshige, 2017-05-05 01:25:06]

Description was changed from

==========
Remove EventSender from ImageLoader

BUG=
==========

to

==========
Remove EventSender from ImageLoader

Previous attempt: https://codereview.chromium.org/1833303002/

BUG=
==========

[hiroshige, 2017-05-05 01:30:51]

Description was changed from

==========
Remove EventSender from ImageLoader

Previous attempt: https://codereview.chromium.org/1833303002/

BUG=
==========

to

==========
Remove EventSender from ImageLoader

Previous attempt: https://codereview.chromium.org/1833303002/

BUG=624697
==========

[hiroshige, 2017-05-05 02:06:34]

Description was changed from

==========
Remove EventSender from ImageLoader

Previous attempt: https://codereview.chromium.org/1833303002/

BUG=624697
==========

to

==========
Remove EventSender from ImageLoader

Previous attempt: https://codereview.chromium.org/1833303002/
https://codereview.chromium.org/1515963005/

BUG=624697
==========

[commit-bot: I haz the power, 2017-05-05 02:42:46]

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

[commit-bot: I haz the power, 2017-05-05 02:42:47]

Dry run: Try jobs failed on following builders:
  linux_chromium_rel_ng on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  mac_chromium_rel_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[hiroshige, 2017-05-05 19:36:53]

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

[commit-bot: I haz the power, 2017-05-05 19:37:46]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[hiroshige, 2017-05-05 20:17:04]

Description was changed from

==========
Remove EventSender from ImageLoader

Previous attempt: https://codereview.chromium.org/1833303002/
https://codereview.chromium.org/1515963005/

BUG=624697
==========

to

==========
Remove EventSender from ImageLoader

Instead of using EventSender, this CL schedules ImageLoader's
load and error events using PostCancellableTask.
has_pending_load_event_ and has_pending_error_event_ booleans are
replaced with TaskHandle to the cancellable tasks and IsActive() calls.

Test changes:
stop-loading.html:
  testharness.js waits for the window load event before finishing.
  Previously, we call window.stop() in <img> load event, but window
  load event is fired, because the <img> load event is fired from
  Document::ImplicitClose() via EventSender. At that time window.stop()
  doesn't stop the window load event.
  After this CL, <img> load event is fired separately from
  Document::ImplicitClose(), and thus window.stop() stops the window
  load event.
  To work around this, this CL triggers window load event explicitly
  just to signal testharness.js to finish.

http/tests/loading/preload-image-sizes-2x.html and
http/tests/loading/preload-picture-sizes-2x.html:
  The tests uses srcset-helper.js that reloads the page with empty
  cache in the window load event.
  Because this CL changes the timing of the window load event, this
  causes some asynchronous tasks that cause new image loading to be
  scheduled before window load event and executed after that, causing
  some images left on the cache before reloading starts.
  This CL works around the issue by waiting a little bit for those
  tasks to be executed, and then clearing the cache and reloading the
  page.

BUG=624697
==========

[hiroshige, 2017-05-05 20:17:04]

hiroshige@chromium.org changed reviewers:
+ japhet@chromium.org, kinuko@chromium.org, kouhei@chromium.org,
tzik@chromium.org, yhirano@chromium.org

[hiroshige, 2017-05-05 20:18:40]

PTAL
japhet@, yhirano@, kinuko@, kouhei@ for loading.

tzik@, is TaskHandle::IsActive() guaranteed to be false
(or true?) when the corresponding cancellable task is
being executed?

[hiroshige, 2017-05-05 20:20:01]

Description was changed from

==========
Remove EventSender from ImageLoader

Instead of using EventSender, this CL schedules ImageLoader's
load and error events using PostCancellableTask.
has_pending_load_event_ and has_pending_error_event_ booleans are
replaced with TaskHandle to the cancellable tasks and IsActive() calls.

Test changes:
stop-loading.html:
  testharness.js waits for the window load event before finishing.
  Previously, we call window.stop() in <img> load event, but window
  load event is fired, because the <img> load event is fired from
  Document::ImplicitClose() via EventSender. At that time window.stop()
  doesn't stop the window load event.
  After this CL, <img> load event is fired separately from
  Document::ImplicitClose(), and thus window.stop() stops the window
  load event.
  To work around this, this CL triggers window load event explicitly
  just to signal testharness.js to finish.

http/tests/loading/preload-image-sizes-2x.html and
http/tests/loading/preload-picture-sizes-2x.html:
  The tests uses srcset-helper.js that reloads the page with empty
  cache in the window load event.
  Because this CL changes the timing of the window load event, this
  causes some asynchronous tasks that cause new image loading to be
  scheduled before window load event and executed after that, causing
  some images left on the cache before reloading starts.
  This CL works around the issue by waiting a little bit for those
  tasks to be executed, and then clearing the cache and reloading the
  page.

BUG=624697
==========

to

==========
Remove EventSender from ImageLoader

Instead of using EventSender, this CL schedules ImageLoader's
load and error events using PostCancellableTask.
has_pending_load_event_ and has_pending_error_event_ booleans are
replaced with TaskHandle to the cancellable tasks and IsActive() calls.

This CL removes the dependencies between Document's load event and
<img> load events via EventSender.

This CL removes EventSender.h as ImageLoader was the last user of that.

Test changes:
stop-loading.html:
  testharness.js waits for the window load event before finishing.
  Previously, we call window.stop() in <img> load event, but window
  load event is fired, because the <img> load event is fired from
  Document::ImplicitClose() via EventSender. At that time window.stop()
  doesn't stop the window load event.
  After this CL, <img> load event is fired separately from
  Document::ImplicitClose(), and thus window.stop() stops the window
  load event.
  To work around this, this CL triggers window load event explicitly
  just to signal testharness.js to finish.

http/tests/loading/preload-image-sizes-2x.html and
http/tests/loading/preload-picture-sizes-2x.html:
  The tests uses srcset-helper.js that reloads the page with empty
  cache in the window load event.
  Because this CL changes the timing of the window load event, this
  causes some asynchronous tasks that cause new image loading to be
  scheduled before window load event and executed after that, causing
  some images left on the cache before reloading starts.
  This CL works around the issue by waiting a little bit for those
  tasks to be executed, and then clearing the cache and reloading the
  page.

BUG=624697
==========

[commit-bot: I haz the power, 2017-05-05 23:01:47]

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

[commit-bot: I haz the power, 2017-05-05 23:01:47]

Dry run: Try jobs failed on following builders:
  linux_android_rel_ng on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)

[hiroshige, 2017-05-05 23:12:03]

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

[commit-bot: I haz the power, 2017-05-05 23:13:02]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-06 01:36:21]

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

[commit-bot: I haz the power, 2017-05-06 01:36:22]

Dry run: Try jobs failed on following builders:
  linux_android_rel_ng on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)

[kinuko, 2017-05-08 09:24:24]

Looking good.

https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
File third_party/WebKit/LayoutTests/http/tests/multipart/stop-loading.html
(right):

https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
third_party/WebKit/LayoutTests/http/tests/multipart/stop-loading.html:16: // We
emulate window load event to signal testharness.js that we don't
nit: that -> so that?

https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
File third_party/WebKit/LayoutTests/http/tests/resources/srcset-helper.js
(right):

https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
third_party/WebKit/LayoutTests/http/tests/resources/srcset-helper.js:34: },
300);
This intuitively feels a bit sketchy, is 300 chosen arbitrarily? Would it be
hard to make this deterministic?

[kinuko, 2017-05-08 09:25:21]

On 2017/05/08 09:24:24, kinuko wrote:
> Looking good.

(And really great to see the CL that's going to remove EventSender!)

>
https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
> File third_party/WebKit/LayoutTests/http/tests/multipart/stop-loading.html
> (right):
> 
>
https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
> third_party/WebKit/LayoutTests/http/tests/multipart/stop-loading.html:16: //
We
> emulate window load event to signal testharness.js that we don't
> nit: that -> so that?
> 
>
https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
> File third_party/WebKit/LayoutTests/http/tests/resources/srcset-helper.js
> (right):
> 
>
https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
> third_party/WebKit/LayoutTests/http/tests/resources/srcset-helper.js:34: },
> 300);
> This intuitively feels a bit sketchy, is 300 chosen arbitrarily? Would it be
> hard to make this deterministic?

[kouhei (in TOK), 2017-05-08 11:54:26]

lgtm

https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
File third_party/WebKit/LayoutTests/http/tests/multipart/stop-loading.html
(right):

https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
third_party/WebKit/LayoutTests/http/tests/multipart/stop-loading.html:16: // We
emulate window load event to signal testharness.js that we don't
On 2017/05/08 09:24:24, kinuko wrote:
> nit: that -> so that?
"that" seems correct here?

https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
File third_party/WebKit/LayoutTests/http/tests/resources/srcset-helper.js
(right):

https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
third_party/WebKit/LayoutTests/http/tests/resources/srcset-helper.js:34: },
300);
On 2017/05/08 09:24:24, kinuko wrote:
> This intuitively feels a bit sketchy, is 300 chosen arbitrarily? Would it be
> hard to make this deterministic?

Tip: use requestAnimationFrame?

[hiroshige, 2017-05-08 19:23:11]

https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
File third_party/WebKit/LayoutTests/http/tests/multipart/stop-loading.html
(right):

https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
third_party/WebKit/LayoutTests/http/tests/multipart/stop-loading.html:16: // We
emulate window load event to signal testharness.js that we don't
On 2017/05/08 11:54:25, kouhei (on transit) wrote:
> On 2017/05/08 09:24:24, kinuko wrote:
> > nit: that -> so that?
> "that" seems correct here?

Either looks fine to me (with different but acceptable meanings) but I'm not a
English expert.

https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
File third_party/WebKit/LayoutTests/http/tests/resources/srcset-helper.js
(right):

https://codereview.chromium.org/2863763003/diff/40001/third_party/WebKit/Layo...
third_party/WebKit/LayoutTests/http/tests/resources/srcset-helper.js:34: },
300);
On 2017/05/08 11:54:25, kouhei (on transit) wrote:
> On 2017/05/08 09:24:24, kinuko wrote:
> This intuitively feels a bit sketchy, is 300 chosen arbitrarily? Would it be
> hard to make this deterministic?
I think we can make this deterministic by using iframes, i.e. set scale factor
in the main HTML and then after that start loading the iframe that contains the
tests.

However, this requires changes to 9 test HTMLs under http/tests/loading that use
srcset-helper.js.
Also, about 40 tests are using srcset-helper.js under fast/.
(They are not affected by this CL because they are not interested in preloading
though)

Therefore I chose to add workaround here not to block this CL by the test
refactoring.

> Tip: use requestAnimationFrame?
requestAnimationFrame didn't work :(
setTimeout(, 0) works.

[kinuko, 2017-05-09 00:02:57]

k, lgtm. thanks!

[kinuko, 2017-05-09 00:03:03]

k, lgtm. thanks!

[tzik, 2017-05-09 03:13:10]

On 2017/05/05 20:18:40, hiroshige wrote:
> PTAL
> japhet@, yhirano@, kinuko@, kouhei@ for loading.
> 
> tzik@, is TaskHandle::IsActive() guaranteed to be false
> (or true?) when the corresponding cancellable task is
> being executed?

LGTM.
Yes, it's guaranteed to be *false* there.

[hiroshige, 2017-05-10 00:09:42]

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

[commit-bot: I haz the power, 2017-05-10 00:10:48]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-10 02:13:08]

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

[commit-bot: I haz the power, 2017-05-10 02:13:09]

Dry run: Try jobs failed on following builders:
  cast_shell_linux on master.tryserver.chromium.linux (JOB_TIMED_OUT, build has
not started yet; builder either lacks capacity or does not exist (misspelled?))
  chromeos_amd64-generic_chromium_compile_only_ng on
master.tryserver.chromium.linux (JOB_TIMED_OUT, build has not started yet;
builder either lacks capacity or does not exist (misspelled?))
  chromeos_daisy_chromium_compile_only_ng on master.tryserver.chromium.linux
(JOB_TIMED_OUT, build has not started yet; builder either lacks capacity or does
not exist (misspelled?))
  chromium_presubmit on master.tryserver.chromium.linux (JOB_TIMED_OUT, build
has not started yet; builder either lacks capacity or does not exist
(misspelled?))
  linux_chromium_asan_rel_ng on master.tryserver.chromium.linux (JOB_TIMED_OUT,
build has not started yet; builder either lacks capacity or does not exist
(misspelled?))
  linux_chromium_chromeos_ozone_rel_ng on master.tryserver.chromium.linux
(JOB_TIMED_OUT, build has not started yet; builder either lacks capacity or does
not exist (misspelled?))
  linux_chromium_chromeos_rel_ng on master.tryserver.chromium.linux
(JOB_TIMED_OUT, build has not started yet; builder either lacks capacity or does
not exist (misspelled?))
  linux_chromium_compile_dbg_ng on master.tryserver.chromium.linux
(JOB_TIMED_OUT, build has not started yet; builder either lacks capacity or does
not exist (misspelled?))
  linux_chromium_rel_ng on master.tryserver.chromium.linux (JOB_TIMED_OUT, build
has not started yet; builder either lacks capacity or does not exist
(misspelled?))
  linux_chromium_tsan_rel_ng on master.tryserver.chromium.linux (JOB_TIMED_OUT,
build has not started yet; builder either lacks capacity or does not exist
(misspelled?))

[hiroshige, 2017-05-10 16:56:56]

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

[commit-bot: I haz the power, 2017-05-10 16:58:37]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-10 20:05:49]

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

[commit-bot: I haz the power, 2017-05-10 20:05:50]

Dry run: Try jobs failed on following builders:
  linux_chromium_rel_ng on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[hiroshige, 2017-05-10 23:04:26]

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

[commit-bot: I haz the power, 2017-05-10 23:05:41]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[hiroshige, 2017-05-10 23:08:39]

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

[commit-bot: I haz the power, 2017-05-10 23:09:37]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-11 00:34:57]

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

[commit-bot: I haz the power, 2017-05-11 00:34:58]

Dry run: Try jobs failed on following builders:
  linux_chromium_rel_ng on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  mac_chromium_rel_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[hiroshige, 2017-05-11 16:07:03]

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

[commit-bot: I haz the power, 2017-05-11 16:07:54]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-11 16:13:41]

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

[commit-bot: I haz the power, 2017-05-11 16:13:42]

Dry run: Try jobs failed on following builders:
  android_n5x_swarming_rel on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/android_n5x_...)
  linux_android_rel_ng on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)
  chromium_presubmit on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[hiroshige, 2017-05-11 18:22:32]

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

[commit-bot: I haz the power, 2017-05-11 18:23:38]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-11 18:29:26]

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

[commit-bot: I haz the power, 2017-05-11 18:29:27]

Dry run: Try jobs failed on following builders:
  linux_android_rel_ng on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)
  mac_chromium_compile_dbg_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_comp...)
  mac_chromium_rel_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[hiroshige, 2017-05-12 17:31:51]

Description was changed from

==========
Remove EventSender from ImageLoader

Instead of using EventSender, this CL schedules ImageLoader's
load and error events using PostCancellableTask.
has_pending_load_event_ and has_pending_error_event_ booleans are
replaced with TaskHandle to the cancellable tasks and IsActive() calls.

This CL removes the dependencies between Document's load event and
<img> load events via EventSender.

This CL removes EventSender.h as ImageLoader was the last user of that.

Test changes:
stop-loading.html:
  testharness.js waits for the window load event before finishing.
  Previously, we call window.stop() in <img> load event, but window
  load event is fired, because the <img> load event is fired from
  Document::ImplicitClose() via EventSender. At that time window.stop()
  doesn't stop the window load event.
  After this CL, <img> load event is fired separately from
  Document::ImplicitClose(), and thus window.stop() stops the window
  load event.
  To work around this, this CL triggers window load event explicitly
  just to signal testharness.js to finish.

http/tests/loading/preload-image-sizes-2x.html and
http/tests/loading/preload-picture-sizes-2x.html:
  The tests uses srcset-helper.js that reloads the page with empty
  cache in the window load event.
  Because this CL changes the timing of the window load event, this
  causes some asynchronous tasks that cause new image loading to be
  scheduled before window load event and executed after that, causing
  some images left on the cache before reloading starts.
  This CL works around the issue by waiting a little bit for those
  tasks to be executed, and then clearing the cache and reloading the
  page.

BUG=624697
==========

to

==========
Remove EventSender from ImageLoader

Instead of using EventSender, this CL schedules ImageLoader's
load and error events using PostCancellableTask.
has_pending_load_event_ and has_pending_error_event_ booleans are
replaced with TaskHandle to the cancellable tasks and IsActive() calls.

This CL removes the dependencies between Document's load event and
<img> load events via EventSender.

This CL removes EventSender.h as ImageLoader was the last user of that.

Test changes:
stop-loading.html:
  testharness.js waits for the window load event before finishing.
  Previously, we call window.stop() in <img> load event, but window
  load event is fired, because the <img> load event is fired from
  Document::ImplicitClose() via EventSender. At that time window.stop()
  doesn't stop the window load event.
  After this CL, <img> load event is fired separately from
  Document::ImplicitClose(), and thus window.stop() stops the window
  load event.
  To work around this, this CL triggers window load event explicitly
  just to signal testharness.js to finish.

http/tests/loading/preload-image-sizes-2x.html and
http/tests/loading/preload-picture-sizes-2x.html:
  The tests uses srcset-helper.js that reloads the page with empty
  cache in the window load event.
  Because this CL changes the timing of the window load event, this
  causes some asynchronous tasks that cause new image loading to be
  scheduled before window load event and executed after that, causing
  some images left on the cache before reloading starts.
  This CL works around the issue by waiting a little bit for those
  tasks to be executed, and then clearing the cache and reloading the
  page.

BUG=624697, 720268
==========

[hiroshige, 2017-05-19 21:13:37]

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

[commit-bot: I haz the power, 2017-05-19 21:14:38]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-20 01:54:28]

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

[commit-bot: I haz the power, 2017-05-20 01:54:29]

Dry run: Try jobs failed on following builders:
  win_chromium_rel_ng on master.tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[hiroshige, 2017-05-22 17:53:44]

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

[commit-bot: I haz the power, 2017-05-22 17:54:36]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-22 21:15:41]

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

[commit-bot: I haz the power, 2017-05-22 21:15:42]

Dry run: This issue passed the CQ dry run.

[hiroshige, 2017-05-23 19:50:22]

The CQ bit was checked by hiroshige@chromium.org

[hiroshige, 2017-05-23 19:50:22]

The patchset sent to the CQ was uploaded after l-g-t-m from kinuko@chromium.org,
kouhei@chromium.org, tzik@chromium.org
Link to the patchset: https://codereview.chromium.org/2863763003/#ps160001
(title: "Rebase")

[commit-bot: I haz the power, 2017-05-23 19:50:50]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-23 19:54:21]

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

[commit-bot: I haz the power, 2017-05-23 19:54:23]

Try jobs failed on following builders:
  ios-simulator on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-simulator/bui...)
  mac_chromium_rel_ng on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

[hiroshige, 2017-05-23 19:58:17]

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

[commit-bot: I haz the power, 2017-05-23 19:58:51]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[hiroshige, 2017-05-23 20:04:04]

The CQ bit was unchecked by hiroshige@chromium.org

[hiroshige, 2017-05-23 20:04:14]

The CQ bit was checked by hiroshige@chromium.org

[hiroshige, 2017-05-23 20:04:15]

The patchset sent to the CQ was uploaded after l-g-t-m from kinuko@chromium.org,
kouhei@chromium.org, tzik@chromium.org
Link to the patchset: https://codereview.chromium.org/2863763003/#ps180001
(title: "Rebase")

[commit-bot: I haz the power, 2017-05-23 20:05:26]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[hiroshige, 2017-05-23 21:28:03]

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

[commit-bot: I haz the power, 2017-05-23 21:29:44]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[hiroshige, 2017-05-23 22:12:19]

Patchset #11 (id:200001) has been deleted

[hiroshige, 2017-05-23 22:12:29]

The CQ bit was unchecked by hiroshige@chromium.org

[hiroshige, 2017-05-23 22:12:36]

The CQ bit was checked by hiroshige@chromium.org

[hiroshige, 2017-05-23 22:12:36]

The patchset sent to the CQ was uploaded after l-g-t-m from kinuko@chromium.org,
kouhei@chromium.org, tzik@chromium.org
Link to the patchset: https://codereview.chromium.org/2863763003/#ps180001
(title: "Rebase")

[hiroshige, 2017-05-23 22:13:38]

The CQ bit was unchecked by hiroshige@chromium.org

[commit-bot: I haz the power, 2017-05-23 22:13:59]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[hiroshige, 2017-05-23 22:14:17]

The CQ bit was checked by hiroshige@chromium.org

[commit-bot: I haz the power, 2017-05-23 22:15:55]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-23 22:31:32]

CQ is committing da patch.

Bot data: {"patchset_id": 180001, "attempt_start_ts": 1495577657498910,
"parent_rev": "789f8d1d41b5dbba8a252d8b69390f9bd67c83db", "commit_rev":
"da70e32d811fffe4e15728ba858dbdfa3180ed59"}

[commit-bot: I haz the power, 2017-05-23 22:31:46]

Description was changed from

==========
Remove EventSender from ImageLoader

Instead of using EventSender, this CL schedules ImageLoader's
load and error events using PostCancellableTask.
has_pending_load_event_ and has_pending_error_event_ booleans are
replaced with TaskHandle to the cancellable tasks and IsActive() calls.

This CL removes the dependencies between Document's load event and
<img> load events via EventSender.

This CL removes EventSender.h as ImageLoader was the last user of that.

Test changes:
stop-loading.html:
  testharness.js waits for the window load event before finishing.
  Previously, we call window.stop() in <img> load event, but window
  load event is fired, because the <img> load event is fired from
  Document::ImplicitClose() via EventSender. At that time window.stop()
  doesn't stop the window load event.
  After this CL, <img> load event is fired separately from
  Document::ImplicitClose(), and thus window.stop() stops the window
  load event.
  To work around this, this CL triggers window load event explicitly
  just to signal testharness.js to finish.

http/tests/loading/preload-image-sizes-2x.html and
http/tests/loading/preload-picture-sizes-2x.html:
  The tests uses srcset-helper.js that reloads the page with empty
  cache in the window load event.
  Because this CL changes the timing of the window load event, this
  causes some asynchronous tasks that cause new image loading to be
  scheduled before window load event and executed after that, causing
  some images left on the cache before reloading starts.
  This CL works around the issue by waiting a little bit for those
  tasks to be executed, and then clearing the cache and reloading the
  page.

BUG=624697, 720268
==========

to

==========
Remove EventSender from ImageLoader

Instead of using EventSender, this CL schedules ImageLoader's
load and error events using PostCancellableTask.
has_pending_load_event_ and has_pending_error_event_ booleans are
replaced with TaskHandle to the cancellable tasks and IsActive() calls.

This CL removes the dependencies between Document's load event and
<img> load events via EventSender.

This CL removes EventSender.h as ImageLoader was the last user of that.

Test changes:
stop-loading.html:
  testharness.js waits for the window load event before finishing.
  Previously, we call window.stop() in <img> load event, but window
  load event is fired, because the <img> load event is fired from
  Document::ImplicitClose() via EventSender. At that time window.stop()
  doesn't stop the window load event.
  After this CL, <img> load event is fired separately from
  Document::ImplicitClose(), and thus window.stop() stops the window
  load event.
  To work around this, this CL triggers window load event explicitly
  just to signal testharness.js to finish.

http/tests/loading/preload-image-sizes-2x.html and
http/tests/loading/preload-picture-sizes-2x.html:
  The tests uses srcset-helper.js that reloads the page with empty
  cache in the window load event.
  Because this CL changes the timing of the window load event, this
  causes some asynchronous tasks that cause new image loading to be
  scheduled before window load event and executed after that, causing
  some images left on the cache before reloading starts.
  This CL works around the issue by waiting a little bit for those
  tasks to be executed, and then clearing the cache and reloading the
  page.

BUG=624697, 720268

Review-Url: https://codereview.chromium.org/2863763003
Cr-Commit-Position: refs/heads/master@{#474086}
Committed:
https://chromium.googlesource.com/chromium/src/+/da70e32d811fffe4e15728ba858d...
==========

[commit-bot: I haz the power, 2017-05-23 22:31:48]

Committed patchset #10 (id:180001) as
https://chromium.googlesource.com/chromium/src/+/da70e32d811fffe4e15728ba858d...

[yosin_UTC9, 2017-05-24 04:06:12]

A revert of this CL (patchset #10 id:180001) has been created in
https://codereview.chromium.org/2903773002/ by yosin@chromium.org.

The reason for reverting is: This patch probably causes object leaks:

See details in "webkit_tests" of
https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%20Trusty...
.