Don't use --process-per-tab when running layout tests.

Don't use --process-per-tab when running layout tests.

1. RenderFrameHostManager::ShouldTransitionCrossSite first checks
   SiteIsolationPolicy::AreCrossProcessFramesPossible() and if it is true,
   then switches::kProcessPerTab is ignored.

2. SiteIsolationPolicy::AreCrossProcessFramesPossible() returns true
   on all platforms except Android since r448761 which initially landed
   in 58.0.3006.0

1 and 2 taken together mean that --process-per-tab switch is a no-op on
all platforms except Android.  This has been the case for the last 2
milestones.  Therefore let's stop using the no-op switch when running
layout tests.

BUG=477150
Review-Url: https://codereview.chromium.org/2968753003
Cr-Commit-Position: refs/heads/master@{#483809}
Committed: https://chromium.googlesource.com/chromium/src/+/b3b4f35a6de19f1fe00f086a19ec7572e231e5d6

[Łukasz Anforowicz, 2017-06-30 18:19:30]

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

[commit-bot: I haz the power, 2017-06-30 18:19:57]

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, 2017-06-30 19:13:40]

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

[commit-bot: I haz the power, 2017-06-30 19:13:40]

Dry run: This issue passed the CQ dry run.

[Łukasz Anforowicz, 2017-06-30 19:44:51]

lukasza@chromium.org changed reviewers:
+ alexmos@chromium.org

[Łukasz Anforowicz, 2017-06-30 19:44:52]

Alex, can you PTAL?

[Łukasz Anforowicz, 2017-06-30 19:47:30]

+site-isolation-reviews@chromium.org

[alexmos, 2017-06-30 20:34:48]

LGTM!

[Łukasz Anforowicz, 2017-06-30 20:39:16]

The CQ bit was checked by lukasza@chromium.org

[commit-bot: I haz the power, 2017-06-30 20:39:48]

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, 2017-06-30 20:43:52]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1498855156192140, "parent_rev":
"546e2c18b48f26c623cb42879d1210fe2ec74b3d", "commit_rev":
"b3b4f35a6de19f1fe00f086a19ec7572e231e5d6"}

[commit-bot: I haz the power, 2017-06-30 20:44:10]

Description was changed from

==========
Don't use --process-per-tab when running layout tests.

1. RenderFrameHostManager::ShouldTransitionCrossSite first checks
   SiteIsolationPolicy::AreCrossProcessFramesPossible() and if it is true,
   then switches::kProcessPerTab is ignored.

2. SiteIsolationPolicy::AreCrossProcessFramesPossible() returns true
   on all platforms except Android since r448761 which initially landed
   in 58.0.3006.0

1 and 2 taken together mean that --process-per-tab switch is a no-op on
all platforms except Android.  This has been the case for the last 2
milestones.  Therefore let's stop using the no-op switch when running
layout tests.

BUG=477150
==========

to

==========
Don't use --process-per-tab when running layout tests.

1. RenderFrameHostManager::ShouldTransitionCrossSite first checks
   SiteIsolationPolicy::AreCrossProcessFramesPossible() and if it is true,
   then switches::kProcessPerTab is ignored.

2. SiteIsolationPolicy::AreCrossProcessFramesPossible() returns true
   on all platforms except Android since r448761 which initially landed
   in 58.0.3006.0

1 and 2 taken together mean that --process-per-tab switch is a no-op on
all platforms except Android.  This has been the case for the last 2
milestones.  Therefore let's stop using the no-op switch when running
layout tests.

BUG=477150

Review-Url: https://codereview.chromium.org/2968753003
Cr-Commit-Position: refs/heads/master@{#483809}
Committed:
https://chromium.googlesource.com/chromium/src/+/b3b4f35a6de19f1fe00f086a19ec...
==========

[commit-bot: I haz the power, 2017-06-30 20:44:11]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/b3b4f35a6de19f1fe00f086a19ec...