[Fetch API] Start reading blob only when the reader wants to read contents.

[Fetch API] Start reading blob only when the reader wants to read contents.

BUG=643174
Committed: https://crrev.com/f1ca96c413912ff1768e4274b8b7ac78eb41de64
Cr-Commit-Position: refs/heads/master@{#416923}

[yhirano, 2016-09-02 03:55:20]

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

[commit-bot: I haz the power, 2016-09-02 03:55:33]

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, 2016-09-02 05:22:07]

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

[commit-bot: I haz the power, 2016-09-02 05:22:08]

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_...)

[yhirano, 2016-09-02 08:08:39]

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

[commit-bot: I haz the power, 2016-09-02 08:08:50]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[yhirano, 2016-09-02 09:15:14]

yhirano@chromium.org changed reviewers:
+ hiroshige@chromium.org, jkarlin@chromium.org

[commit-bot: I haz the power, 2016-09-02 09:53:45]

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

[commit-bot: I haz the power, 2016-09-02 09:53:46]

Dry run: This issue passed the CQ dry run.

[jkarlin, 2016-09-02 11:14:52]

Thanks for writing this, I can confirm that this fixes issue 643174 but I don't
know the code well enough to review it.

[yhirano, 2016-09-06 09:36:21]

hiroshige: ping

[hiroshige, 2016-09-07 09:38:03]

Can you add a test that confirms zero-byte read doesn't initiate loading?

https://codereview.chromium.org/2303753003/diff/20001/third_party/WebKit/Sour...
File third_party/WebKit/Source/modules/fetch/FetchFormDataConsumerHandleTest.cpp
(left):

https://codereview.chromium.org/2303753003/diff/20001/third_party/WebKit/Sour...
third_party/WebKit/Source/modules/fetch/FetchFormDataConsumerHandleTest.cpp:404:
EXPECT_EQ(kOk, reader->read(nullptr, 0, kNone, &readSize));
Why this line is removed?

[yhirano, 2016-09-07 11:02:54]

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

[commit-bot: I haz the power, 2016-09-07 11:03:18]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[yhirano, 2016-09-07 11:03:24]

> Can you add a test that confirms zero-byte read doesn't initiate loading?
Done.

https://codereview.chromium.org/2303753003/diff/20001/third_party/WebKit/Sour...
File third_party/WebKit/Source/modules/fetch/FetchFormDataConsumerHandleTest.cpp
(left):

https://codereview.chromium.org/2303753003/diff/20001/third_party/WebKit/Sour...
third_party/WebKit/Source/modules/fetch/FetchFormDataConsumerHandleTest.cpp:404:
EXPECT_EQ(kOk, reader->read(nullptr, 0, kNone, &readSize));
On 2016/09/07 09:38:03, hiroshige wrote:
> Why this line is removed?

My change makes this read return kShouldWait, and I don't think the second read
is needed for this test.

[commit-bot: I haz the power, 2016-09-07 12:35:08]

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

[commit-bot: I haz the power, 2016-09-07 12:35:09]

Dry run: This issue passed the CQ dry run.

[hiroshige, 2016-09-07 13:00:41]

lgtm.

[yhirano, 2016-09-07 13:04:15]

The CQ bit was checked by yhirano@chromium.org

[commit-bot: I haz the power, 2016-09-07 13:04:29]

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, 2016-09-07 13:08:24]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-09-07 13:11:04]

Description was changed from

==========
[Fetch API] Start reading blob only when the reader wants to read contents.

BUG=643174
==========

to

==========
[Fetch API] Start reading blob only when the reader wants to read contents.

BUG=643174

Committed: https://crrev.com/f1ca96c413912ff1768e4274b8b7ac78eb41de64
Cr-Commit-Position: refs/heads/master@{#416923}
==========

[commit-bot: I haz the power, 2016-09-07 13:11:05]

Patchset 3 (id:??) landed as
https://crrev.com/f1ca96c413912ff1768e4274b8b7ac78eb41de64
Cr-Commit-Position: refs/heads/master@{#416923}

[lushnikov, 2016-09-08 14:43:43]

A revert of this CL (patchset #3 id:40001) has been created in
https://codereview.chromium.org/2319093004/ by lushnikov@chromium.org.

The reason for reverting is: Speculative revert: this patch is a suspect to
cause Linux MSAN failures:

https://uberchromegw.corp.google.com/i/chromium.webkit/builders/WebKit%20Linu...

The other suspected patch, the only one related to canvas, was reverted and
didn't help..