Reuse cc::PictureLayers when possible for SPv2.

Reuse cc::PictureLayers when possible for SPv2.

The approach is very simple: if the PaintChunk.id's match, then reuse the layer
backing a chunk, and rely on the raster invalidations to invalidate as needed if
content changes or moves relative to the PaintChunk.

BUG=647831
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Committed: https://crrev.com/06af5b6237a576c36a74c607d154b93320985503
Cr-Commit-Position: refs/heads/master@{#420571}

[chrishtr, 2016-09-16 22:03:43]

Description was changed from

==========
none


none


none


none

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

to

==========
none


none


none


none

BUG=
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

[chrishtr, 2016-09-16 22:08:26]

Description was changed from

==========
none


none


none


none

BUG=
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

to

==========
Reuse cc::PictureLayers when possible for SPv2.

BUG=647831
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

[chrishtr, 2016-09-16 22:08:30]

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

[commit-bot: I haz the power, 2016-09-16 22:09:09]

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, 2016-09-16 23:05:53]

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

[commit-bot: I haz the power, 2016-09-16 23:05:54]

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

[chrishtr, 2016-09-17 01:02:39]

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

[commit-bot: I haz the power, 2016-09-17 01:03:15]

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, 2016-09-17 02:03:15]

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

[commit-bot: I haz the power, 2016-09-17 02:03:16]

Dry run: Try jobs failed on following builders:
  linux_layout_tests_slimming_paint_v2 on master.tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_layout_te...)

[chrishtr, 2016-09-20 22:38:46]

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

[commit-bot: I haz the power, 2016-09-20 22:39:37]

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

[chrishtr, 2016-09-20 22:40:46]

Description was changed from

==========
Reuse cc::PictureLayers when possible for SPv2.

BUG=647831
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

to

==========
Reuse cc::PictureLayers when possible for SPv2.

The approach is very simple: if the PaintChunk.id's match, then reuse the layer
backing a chunk, and rely on the raster invalidations to invalidate as needed if
content changes or moves relative to the PaintChunk.

BUG=647831
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

[chrishtr, 2016-09-20 22:40:57]

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

[chrishtr, 2016-09-20 22:40:58]

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
File third_party/WebKit/Source/core/paint/PaintInvalidator.cpp (right):

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/paint/PaintInvalidator.cpp:59: if
(RuntimeEnabledFeatures::slimmingPaintV2Enabled())
In a followup I propose to simplify the code in this class for SPv2. SPv2
doesn't need the notion of a
paint invalidation container at all. WDYT?

[commit-bot: I haz the power, 2016-09-20 22:51:50]

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

[commit-bot: I haz the power, 2016-09-20 22:51:52]

Dry run: Try jobs failed on following builders:
  android_compile_dbg on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/android_comp...)
  chromeos_x86-generic_chromium_compile_only_ng on
master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromeos_x86-ge...)

[Xianzhu, 2016-09-20 23:13:41]

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
File third_party/WebKit/Source/core/layout/LayoutObject.cpp (right):

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/layout/LayoutObject.cpp:1085:
name.append(String::format(" %p", this));
The output of debugName() is used in layout test outputs, so it should not
include anything that can change between runs.

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
File third_party/WebKit/Source/core/paint/PaintInvalidator.cpp (right):

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/paint/PaintInvalidator.cpp:59: if
(RuntimeEnabledFeatures::slimmingPaintV2Enabled())
On 2016/09/20 22:40:58, chrishtr wrote:
> In a followup I propose to simplify the code in this class for SPv2. SPv2
> doesn't need the notion of a
> paint invalidation container at all. WDYT?

Agreed.

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/paint/PaintInvalidator.cpp:62: bool success =
false;
Nit: don't move this line.

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
File
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp
(right):

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp:208:
}
I'm a bit concerned about performance here. Perhaps we can use the same search
algorithm in PaintController (sequential search + hashmap for out-of-order
search) (not necessarily in this patch).

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
File third_party/WebKit/Source/platform/graphics/paint/PaintArtifact.cpp
(right):

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/platform/graphics/paint/PaintArtifact.cpp:31: if
(drawing.knownToBeOpaque()) {
There seems a problem: the picture may be smaller than the client's visual rect
(which covers all pictures of the client), so one picture is opaque doesn't mean
the whole client visual rect is opaque.

[chrishtr, 2016-09-20 23:43:59]

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
File third_party/WebKit/Source/core/layout/LayoutObject.cpp (right):

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/layout/LayoutObject.cpp:1085:
name.append(String::format(" %p", this));
On 2016/09/20 at 23:13:41, Xianzhu wrote:
> The output of debugName() is used in layout test outputs, so it should not
include anything that can change between runs.

Good point. Removed.

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
File third_party/WebKit/Source/core/paint/PaintInvalidator.cpp (right):

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/paint/PaintInvalidator.cpp:62: bool success =
false;
On 2016/09/20 at 23:13:41, Xianzhu wrote:
> Nit: don't move this line.

Done.

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
File
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp
(right):

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp:208:
}
On 2016/09/20 at 23:13:41, Xianzhu wrote:
> I'm a bit concerned about performance here. Perhaps we can use the same search
algorithm in PaintController (sequential search + hashmap for out-of-order
search) (not necessarily in this patch).

Oh, forgot to add a TODO about this. I agree.

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
File third_party/WebKit/Source/platform/graphics/paint/PaintArtifact.cpp
(right):

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/platform/graphics/paint/PaintArtifact.cpp:31: if
(drawing.knownToBeOpaque()) {
On 2016/09/20 at 23:13:41, Xianzhu wrote:
> There seems a problem: the picture may be smaller than the client's visual
rect (which covers all pictures of the client), so one picture is opaque doesn't
mean the whole client visual rect is opaque.

Good point. Reverted this part.

[chrishtr, 2016-09-20 23:44:04]

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

[commit-bot: I haz the power, 2016-09-20 23:44:35]

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, 2016-09-21 02:05:55]

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

[commit-bot: I haz the power, 2016-09-21 02:05:56]

Dry run: Try jobs failed on following builders:
  linux_layout_tests_slimming_paint_v2 on master.tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_layout_te...)

[pdr., 2016-09-21 02:46:14]

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
File third_party/WebKit/Source/core/paint/PaintInvalidator.cpp (right):

https://codereview.chromium.org/2345233004/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/core/paint/PaintInvalidator.cpp:62: bool success =
false;
Nit: move this back down

https://codereview.chromium.org/2345233004/diff/120001/content/shell/renderer...
File content/shell/renderer/layout_test/blink_test_runner.cc (right):

https://codereview.chromium.org/2345233004/diff/120001/content/shell/renderer...
content/shell/renderer/layout_test/blink_test_runner.cc:582: if
(!is_main_window_ || !render_view()->GetMainRenderFrame()) {
Nit: I think the indentation got lost here.

https://codereview.chromium.org/2345233004/diff/120001/third_party/WebKit/Sou...
File
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp
(right):

https://codereview.chromium.org/2345233004/diff/120001/third_party/WebKit/Sou...
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp:228:
contentLayerClient->SetPaintableRegion(gfx::Rect(combinedBounds.size()));
Can the combined bounds grow?

https://codereview.chromium.org/2345233004/diff/120001/third_party/WebKit/Sou...
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp:553:

DCHECK above that m_newContentLayerClients is empty?

https://codereview.chromium.org/2345233004/diff/120001/third_party/WebKit/Sou...
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp:557:
scoped_refptr<cc::Layer> layer = layerForPaintChunk(paintArtifact, paintChunk,
layerOffset);
Do we need the m_newContentLayerClients member since it's just used locally
here? IOW, can we just create a local for newContentLayerClients and pass it
into layerForPaintChunk?

[chrishtr, 2016-09-21 22:34:42]

See also the change to PaintInvalidationCapableScrollableArea.

https://codereview.chromium.org/2345233004/diff/120001/content/shell/renderer...
File content/shell/renderer/layout_test/blink_test_runner.cc (right):

https://codereview.chromium.org/2345233004/diff/120001/content/shell/renderer...
content/shell/renderer/layout_test/blink_test_runner.cc:582: if
(!is_main_window_ || !render_view()->GetMainRenderFrame()) {
On 2016/09/21 at 02:46:13, pdr. wrote:
> Nit: I think the indentation got lost here.

Fixed.

https://codereview.chromium.org/2345233004/diff/120001/third_party/WebKit/Sou...
File
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp
(right):

https://codereview.chromium.org/2345233004/diff/120001/third_party/WebKit/Sou...
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp:228:
contentLayerClient->SetPaintableRegion(gfx::Rect(combinedBounds.size()));
On 2016/09/21 at 02:46:13, pdr. wrote:
> Can the combined bounds grow?

Yes.

https://codereview.chromium.org/2345233004/diff/120001/third_party/WebKit/Sou...
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp:553:

On 2016/09/21 at 02:46:13, pdr. wrote:
> DCHECK above that m_newContentLayerClients is empty?

Now unnecessary due to the below suggestion.

https://codereview.chromium.org/2345233004/diff/120001/third_party/WebKit/Sou...
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp:557:
scoped_refptr<cc::Layer> layer = layerForPaintChunk(paintArtifact, paintChunk,
layerOffset);
On 2016/09/21 at 02:46:13, pdr. wrote:
> Do we need the m_newContentLayerClients member since it's just used locally
here? IOW, can we just create a local for newContentLayerClients and pass it
into layerForPaintChunk?

Done.

[chrishtr, 2016-09-21 22:41:39]

Update to the latest patchset.

[pdr., 2016-09-21 22:45:12]

LGTM

https://codereview.chromium.org/2345233004/diff/220001/third_party/WebKit/Sou...
File
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp
(right):

https://codereview.chromium.org/2345233004/diff/220001/third_party/WebKit/Sou...
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp:205:
// TODO(chrishtr): for now, just using a linear walk. In the future we can
optimize this by using the same techniques used in
Xianzhu, I think this looks good but can you triple-check?

https://codereview.chromium.org/2345233004/diff/220001/third_party/WebKit/Sou...
File
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h
(right):

https://codereview.chromium.org/2345233004/diff/220001/third_party/WebKit/Sou...
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h:86:
Vector<std::unique_ptr<ContentLayerClientImpl>> m_currentContentLayerClients;
Nit: revert this back to m_contentLayerClients

[Xianzhu, 2016-09-21 23:17:55]

lgtm

[chrishtr, 2016-09-22 16:49:30]

The CQ bit was checked by chrishtr@chromium.org

[chrishtr, 2016-09-22 16:49:31]

The patchset sent to the CQ was uploaded after l-g-t-m from pdr@chromium.org,
wangxianzhu@chromium.org
Link to the patchset: https://codereview.chromium.org/2345233004/#ps240001
(title: "none")

[commit-bot: I haz the power, 2016-09-22 16:49:53]

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

[chrishtr, 2016-09-22 16:50:17]

The CQ bit was unchecked by chrishtr@chromium.org

[chrishtr, 2016-09-22 16:51:33]

https://codereview.chromium.org/2345233004/diff/220001/third_party/WebKit/Sou...
File
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp
(right):

https://codereview.chromium.org/2345233004/diff/220001/third_party/WebKit/Sou...
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp:205:
// TODO(chrishtr): for now, just using a linear walk. In the future we can
optimize this by using the same techniques used in
On 2016/09/21 at 22:45:12, pdr. wrote:
> Xianzhu, I think this looks good but can you triple-check?

FYI he commented on this earlier in the code review.

https://codereview.chromium.org/2345233004/diff/220001/third_party/WebKit/Sou...
File
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h
(right):

https://codereview.chromium.org/2345233004/diff/220001/third_party/WebKit/Sou...
third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.h:86:
Vector<std::unique_ptr<ContentLayerClientImpl>> m_currentContentLayerClients;
On 2016/09/21 at 22:45:12, pdr. wrote:
> Nit: revert this back to m_contentLayerClients

Done.

[chrishtr, 2016-09-22 17:05:15]

The CQ bit was checked by chrishtr@chromium.org

[chrishtr, 2016-09-22 17:05:15]

The patchset sent to the CQ was uploaded after l-g-t-m from pdr@chromium.org,
wangxianzhu@chromium.org
Link to the patchset: https://codereview.chromium.org/2345233004/#ps260001
(title: "none")

[commit-bot: I haz the power, 2016-09-22 17:05:30]

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, 2016-09-22 17:58:37]

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

[commit-bot: I haz the power, 2016-09-22 17:58:38]

Try jobs failed on following builders:
  linux_layout_tests_slimming_paint_v2 on master.tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_layout_te...)

[chrishtr, 2016-09-22 18:24:39]

The CQ bit was checked by chrishtr@chromium.org

[chrishtr, 2016-09-22 18:24:40]

The patchset sent to the CQ was uploaded after l-g-t-m from pdr@chromium.org,
wangxianzhu@chromium.org
Link to the patchset: https://codereview.chromium.org/2345233004/#ps280001
(title: "none")

[commit-bot: I haz the power, 2016-09-22 18:25:18]

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, 2016-09-22 18:56:47]

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

[commit-bot: I haz the power, 2016-09-22 18:56:48]

Try jobs failed on following builders:
  linux_layout_tests_slimming_paint_v2 on master.tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_layout_te...)

[chrishtr, 2016-09-22 19:12:27]

The CQ bit was checked by chrishtr@chromium.org

[commit-bot: I haz the power, 2016-09-22 19:13:03]

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, 2016-09-22 20:08:03]

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

[commit-bot: I haz the power, 2016-09-22 20:08:05]

Try jobs failed on following builders:
  linux_layout_tests_slimming_paint_v2 on master.tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_layout_te...)

[chrishtr, 2016-09-22 21:13:32]

The CQ bit was checked by chrishtr@chromium.org

[chrishtr, 2016-09-22 21:13:33]

The patchset sent to the CQ was uploaded after l-g-t-m from pdr@chromium.org,
wangxianzhu@chromium.org
Link to the patchset: https://codereview.chromium.org/2345233004/#ps300001
(title: "none")

[commit-bot: I haz the power, 2016-09-22 21:14:05]

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, 2016-09-22 21:48:01]

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

[commit-bot: I haz the power, 2016-09-22 21:48:03]

Try jobs failed on following builders:
  linux_layout_tests_slimming_paint_v2 on master.tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_layout_te...)

[chrishtr, 2016-09-22 22:09:00]

The CQ bit was checked by chrishtr@chromium.org

[chrishtr, 2016-09-22 22:09:00]

The patchset sent to the CQ was uploaded after l-g-t-m from pdr@chromium.org,
wangxianzhu@chromium.org
Link to the patchset: https://codereview.chromium.org/2345233004/#ps320001
(title: "none")

[commit-bot: I haz the power, 2016-09-22 22:09:35]

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

[chrishtr, 2016-09-22 23:04:47]

The CQ bit was checked by chrishtr@chromium.org

[chrishtr, 2016-09-22 23:04:47]

The patchset sent to the CQ was uploaded after l-g-t-m from pdr@chromium.org,
wangxianzhu@chromium.org
Link to the patchset: https://codereview.chromium.org/2345233004/#ps340001
(title: "none")

[commit-bot: I haz the power, 2016-09-22 23:05:24]

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, 2016-09-23 00:01:29]

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

[commit-bot: I haz the power, 2016-09-23 00:01:30]

Try jobs failed on following builders:
  linux_layout_tests_slimming_paint_v2 on master.tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_layout_te...)

[chrishtr, 2016-09-23 00:09:23]

The CQ bit was checked by chrishtr@chromium.org

[chrishtr, 2016-09-23 00:09:24]

The patchset sent to the CQ was uploaded after l-g-t-m from pdr@chromium.org,
wangxianzhu@chromium.org
Link to the patchset: https://codereview.chromium.org/2345233004/#ps360001
(title: "none")

[commit-bot: I haz the power, 2016-09-23 00:09:55]

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, 2016-09-23 00:55:20]

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

[commit-bot: I haz the power, 2016-09-23 00:55:22]

Try jobs failed on following builders:
  linux_layout_tests_slimming_paint_v2 on master.tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_layout_te...)

[chrishtr, 2016-09-23 02:17:10]

The CQ bit was checked by chrishtr@chromium.org

[chrishtr, 2016-09-23 02:17:11]

The patchset sent to the CQ was uploaded after l-g-t-m from pdr@chromium.org,
wangxianzhu@chromium.org
Link to the patchset: https://codereview.chromium.org/2345233004/#ps380001
(title: "none")

[commit-bot: I haz the power, 2016-09-23 02:17:49]

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, 2016-09-23 03:53:52]

Committed patchset #20 (id:380001)

[commit-bot: I haz the power, 2016-09-23 03:56:03]

Description was changed from

==========
Reuse cc::PictureLayers when possible for SPv2.

The approach is very simple: if the PaintChunk.id's match, then reuse the layer
backing a chunk, and rely on the raster invalidations to invalidate as needed if
content changes or moves relative to the PaintChunk.

BUG=647831
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

to

==========
Reuse cc::PictureLayers when possible for SPv2.

The approach is very simple: if the PaintChunk.id's match, then reuse the layer
backing a chunk, and rely on the raster invalidations to invalidate as needed if
content changes or moves relative to the PaintChunk.

BUG=647831
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Committed: https://crrev.com/06af5b6237a576c36a74c607d154b93320985503
Cr-Commit-Position: refs/heads/master@{#420571}
==========

[commit-bot: I haz the power, 2016-09-23 03:56:05]

Patchset 20 (id:??) landed as
https://crrev.com/06af5b6237a576c36a74c607d154b93320985503
Cr-Commit-Position: refs/heads/master@{#420571}