Remove redundant update of viewport layer types

Remove redundant update of viewport layer types

LayerImpl's viewport layer types depend on (1) LayerTreeImpl's viewport
layers and (2) LayerImpl's scroll_clip_layer. [1] added code to update
the layer type when either (1) or (2) change.

With the refactoring of [2], LayerImpl's properties such as
scroll_clip_layer are always set before LayerTreeImpl's viewport layers
are updated. This patch removes an unnecessary call to
LayerTreeImpl::UpdateViewportLayerTypes from LayerImpl::SetScrollClipLayer
and proves it is safe with a new DCHECK.

Add a cache of LayerImpl's viewport layer type
[1] https://chromium.googlesource.com/chromium/src/+/6280cc1d5a1dccfbe23ca438eed862e245f18614

Harmonize LayerTreeHost/LayerTreeHostImpl synchronization steps
[2] https://chromium.googlesource.com/chromium/src/+/80ecb98035a6654fff02e86877be39f51fcc3d54

BUG=693740
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2882403002
Cr-Commit-Position: refs/heads/master@{#472150}
Committed: https://chromium.googlesource.com/chromium/src/+/b4d70c2b28f321a94a52615c95692b6da8738783

[pdr., 2017-05-16 04:34:28]

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

[commit-bot: I haz the power, 2017-05-16 04:34:59]

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, 2017-05-16 06:24:50]

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

[commit-bot: I haz the power, 2017-05-16 06:24:51]

Dry run: Try jobs failed on following builders:
  win_chromium_x64_rel_ng on master.tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[pdr., 2017-05-16 14:33:06]

pdr@chromium.org changed reviewers:
+ chrishtr@chromium.org, enne@chromium.org

[enne (OOO), 2017-05-16 17:22:08]

!!!!!!!!!!!!!!!

lgtm

[pdr., 2017-05-16 17:27:25]

The CQ bit was checked by pdr@chromium.org

[commit-bot: I haz the power, 2017-05-16 17:28:38]

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, 2017-05-16 17:48:26]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1494955645519640, "parent_rev":
"b9946bb24dac07cb38b87697114678f6f416b20d", "commit_rev":
"b4d70c2b28f321a94a52615c95692b6da8738783"}

[commit-bot: I haz the power, 2017-05-16 17:48:37]

Description was changed from

==========
Remove redundant update of viewport layer types

LayerImpl's viewport layer types depend on (1) LayerTreeImpl's viewport
layers and (2) LayerImpl's scroll_clip_layer. [1] added code to update
the layer type when either (1) or (2) change.

With the refactoring of [2], LayerImpl's properties such as
scroll_clip_layer are always set before LayerTreeImpl's viewport layers
are updated. This patch removes an unnecessary call to
LayerTreeImpl::UpdateViewportLayerTypes from LayerImpl::SetScrollClipLayer
and proves it is safe with a new DCHECK.

Add a cache of LayerImpl's viewport layer type
[1]
https://chromium.googlesource.com/chromium/src/+/6280cc1d5a1dccfbe23ca438eed8...

Harmonize LayerTreeHost/LayerTreeHostImpl synchronization steps
[2]
https://chromium.googlesource.com/chromium/src/+/80ecb98035a6654fff02e86877be...

BUG=693740
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

to

==========
Remove redundant update of viewport layer types

LayerImpl's viewport layer types depend on (1) LayerTreeImpl's viewport
layers and (2) LayerImpl's scroll_clip_layer. [1] added code to update
the layer type when either (1) or (2) change.

With the refactoring of [2], LayerImpl's properties such as
scroll_clip_layer are always set before LayerTreeImpl's viewport layers
are updated. This patch removes an unnecessary call to
LayerTreeImpl::UpdateViewportLayerTypes from LayerImpl::SetScrollClipLayer
and proves it is safe with a new DCHECK.

Add a cache of LayerImpl's viewport layer type
[1]
https://chromium.googlesource.com/chromium/src/+/6280cc1d5a1dccfbe23ca438eed8...

Harmonize LayerTreeHost/LayerTreeHostImpl synchronization steps
[2]
https://chromium.googlesource.com/chromium/src/+/80ecb98035a6654fff02e86877be...

BUG=693740
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2882403002
Cr-Commit-Position: refs/heads/master@{#472150}
Committed:
https://chromium.googlesource.com/chromium/src/+/b4d70c2b28f321a94a52615c9569...
==========

[commit-bot: I haz the power, 2017-05-16 17:48:38]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/b4d70c2b28f321a94a52615c9569...