Switch canvas.toBlob from idle-periods implementation to threaded implementation to allow experimen…

Switch canvas.toBlob from idle-periods implementation to threaded
implementation to allow experimenting.

Based on repeated experiments of both idle-periods implementation and
threaded implementation for png image encoding on a variety of perf
trybots, we find that the idle-periods implementation does not have
observable improvement on reducing the negative impact of canvas.toBlob
on the smoothness of animation, even on low-end devices; meanwhile, the
threaded implementation runs canvas.toBlob significantly faster and does
not have the risk of indefinitely delaying the image encoding task like
the idle-periods implementation. Therefore, we decide to switch
canvas.toBlob to its threaded implementation.

This CL will allow people (recipients of intent-to-ship letter) to try out
 canvas.toBlob in its threaded implementation by simply turning on
--enable-experimental-canvas-features flag. Not only that, we also allow
some grace periods to check if the related performance tests on dashboard
have any regression. After approvals from API owners, we will follow with
another CL that completely deletes the idle-periods implementation and
merges the CanvasAsyncBlobCreator back to HTMLCanvasElement to
reduce redundant codes.

BUG=523414
Committed: https://crrev.com/9cbf936a9bc9102b2c9f9a7f6311b53747c2bd52
Cr-Commit-Position: refs/heads/master@{#362787}

[xlai (Olivia), 2015-12-01 18:47:42]

xlai@chromium.org changed reviewers:
+ junov@chromium.org

[xlai (Olivia), 2015-12-01 18:47:42]

junov@: After Intent-to-ship letter is sent, probably there will be ppl who want
to try out the feature. In that case, we should let them try out the threaded
implementation instead of the idle-periods implementation, because the former is
the version that we want to ship. Another reason is that we switch it back to
threaded and can observe the perf dashboard to see if there's regression.

[Justin Novosad, 2015-12-01 19:38:03]

Please respect the 72col limit on CL descriptions.

https://codereview.chromium.org/1491653002/diff/1/third_party/WebKit/Source/c...
File third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp (right):

https://codereview.chromium.org/1491653002/diff/1/third_party/WebKit/Source/c...
third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp:565: // TODO(xlai):
After Intent-to-Ship is approved, remove idle-periods version of implementation
completely
Create a crbug about this so we don't forget.

https://codereview.chromium.org/1491653002/diff/1/third_party/WebKit/Source/c...
third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp:568: // } else {
Don't commit commented-out code

[xlai (Olivia), 2015-12-01 20:21:45]

Description was changed from

==========
Switch canvas.toBlob from idle-periods implementation to threaded implementation
to allow experimenting.

Based on repeated experiments of both idle-periods implementation and threaded
implementation for png image
encoding on a variety of perf trybots, we find that the idle-periods
implementation does not have
observable improvement on reducing the negative impact of canvas.toBlob on the
smoothness of animation, even
on low-end devices; meanwhile, the threaded implementation runs canvas.toBlob
significantly faster and does
not have the risk of indefinitely delaying the image encoding task like the
idle-periods implementation.
Therefore, we decide to switch canvas.toBlob to its threaded implementation.

This CL will allow people (recipients of intent-to-ship letter) to try out
canvas.toBlob in its threaded
implementation by simply turning on --enable-experimental-canvas-features flag.
Not only that, we also allow
some grace periods to check if the related performance tests on dashboard have
any regression. After
approvals from API owners, we will follow with another CL that completely
deletes the idle-periods
implementation and merges the CanvasAsyncBlobCreator back to HTMLCanvasElement
to reduce redundant codes.

BUG=523414
==========

to

==========
Switch canvas.toBlob from idle-periods implementation to threaded               
                             
implementation to allow experimenting.                                          
                                
                                                                                
                                
Based on repeated experiments of both idle-periods implementation and           
                                
threaded implementation for png image encoding on a variety of perf             
                                
trybots, we find that the idle-periods implementation does not have             
                                
observable improvement on reducing the negative impact of canvas.toBlob         
                                
on the smoothness of animation, even on low-end devices; meanwhile, the         
                                
threaded implementation runs canvas.toBlob significantly faster and does        
                                
not have the risk of indefinitely delaying the image encoding task like         
                                
the idle-periods implementation. Therefore, we decide to switch                 
                                
canvas.toBlob to its threaded implementation.                                   
                                
                                                                                
                                
This CL will allow people (recipients of intent-to-ship letter) to try out      
                                
 canvas.toBlob in its threaded implementation by simply turning on              
                                
--enable-experimental-canvas-features flag. Not only that, we also allow        
                                
some grace periods to check if the related performance tests on dashboard       
                                
have any regression. After approvals from API owners, we will follow with       
                                
another CL that completely deletes the idle-periods implementation and          
                                
merges the CanvasAsyncBlobCreator back to HTMLCanvasElement to                  
                                
reduce redundant codes.

BUG=523414
==========

[Justin Novosad, 2015-12-02 16:06:04]

On 2015/12/01 20:22:52, Olivia wrote:

lgtm

[xlai (Olivia), 2015-12-02 16:07:09]

The CQ bit was checked by xlai@chromium.org

[commit-bot: I haz the power, 2015-12-02 16:07:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1491653002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1491653002/20001

[commit-bot: I haz the power, 2015-12-02 18:25:52]

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

[commit-bot: I haz the power, 2015-12-02 18:25:52]

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

[xlai (Olivia), 2015-12-02 19:40:12]

The CQ bit was checked by xlai@chromium.org

[commit-bot: I haz the power, 2015-12-02 19:40:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1491653002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1491653002/20001

[commit-bot: I haz the power, 2015-12-02 20:56:26]

Description was changed from

==========
Switch canvas.toBlob from idle-periods implementation to threaded               
                             
implementation to allow experimenting.                                          
                                
                                                                                
                                
Based on repeated experiments of both idle-periods implementation and           
                                
threaded implementation for png image encoding on a variety of perf             
                                
trybots, we find that the idle-periods implementation does not have             
                                
observable improvement on reducing the negative impact of canvas.toBlob         
                                
on the smoothness of animation, even on low-end devices; meanwhile, the         
                                
threaded implementation runs canvas.toBlob significantly faster and does        
                                
not have the risk of indefinitely delaying the image encoding task like         
                                
the idle-periods implementation. Therefore, we decide to switch                 
                                
canvas.toBlob to its threaded implementation.                                   
                                
                                                                                
                                
This CL will allow people (recipients of intent-to-ship letter) to try out      
                                
 canvas.toBlob in its threaded implementation by simply turning on              
                                
--enable-experimental-canvas-features flag. Not only that, we also allow        
                                
some grace periods to check if the related performance tests on dashboard       
                                
have any regression. After approvals from API owners, we will follow with       
                                
another CL that completely deletes the idle-periods implementation and          
                                
merges the CanvasAsyncBlobCreator back to HTMLCanvasElement to                  
                                
reduce redundant codes.

BUG=523414
==========

to

==========
Switch canvas.toBlob from idle-periods implementation to threaded               
                             
implementation to allow experimenting.                                          
                                
                                                                                
                                
Based on repeated experiments of both idle-periods implementation and           
                                
threaded implementation for png image encoding on a variety of perf             
                                
trybots, we find that the idle-periods implementation does not have             
                                
observable improvement on reducing the negative impact of canvas.toBlob         
                                
on the smoothness of animation, even on low-end devices; meanwhile, the         
                                
threaded implementation runs canvas.toBlob significantly faster and does        
                                
not have the risk of indefinitely delaying the image encoding task like         
                                
the idle-periods implementation. Therefore, we decide to switch                 
                                
canvas.toBlob to its threaded implementation.                                   
                                
                                                                                
                                
This CL will allow people (recipients of intent-to-ship letter) to try out      
                                
 canvas.toBlob in its threaded implementation by simply turning on              
                                
--enable-experimental-canvas-features flag. Not only that, we also allow        
                                
some grace periods to check if the related performance tests on dashboard       
                                
have any regression. After approvals from API owners, we will follow with       
                                
another CL that completely deletes the idle-periods implementation and          
                                
merges the CanvasAsyncBlobCreator back to HTMLCanvasElement to                  
                                
reduce redundant codes.

BUG=523414
==========

[commit-bot: I haz the power, 2015-12-02 20:56:27]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-12-02 20:57:27]

Description was changed from

==========
Switch canvas.toBlob from idle-periods implementation to threaded               
                             
implementation to allow experimenting.                                          
                                
                                                                                
                                
Based on repeated experiments of both idle-periods implementation and           
                                
threaded implementation for png image encoding on a variety of perf             
                                
trybots, we find that the idle-periods implementation does not have             
                                
observable improvement on reducing the negative impact of canvas.toBlob         
                                
on the smoothness of animation, even on low-end devices; meanwhile, the         
                                
threaded implementation runs canvas.toBlob significantly faster and does        
                                
not have the risk of indefinitely delaying the image encoding task like         
                                
the idle-periods implementation. Therefore, we decide to switch                 
                                
canvas.toBlob to its threaded implementation.                                   
                                
                                                                                
                                
This CL will allow people (recipients of intent-to-ship letter) to try out      
                                
 canvas.toBlob in its threaded implementation by simply turning on              
                                
--enable-experimental-canvas-features flag. Not only that, we also allow        
                                
some grace periods to check if the related performance tests on dashboard       
                                
have any regression. After approvals from API owners, we will follow with       
                                
another CL that completely deletes the idle-periods implementation and          
                                
merges the CanvasAsyncBlobCreator back to HTMLCanvasElement to                  
                                
reduce redundant codes.

BUG=523414
==========

to

==========
Switch canvas.toBlob from idle-periods implementation to threaded
implementation to allow experimenting.

Based on repeated experiments of both idle-periods implementation and
threaded implementation for png image encoding on a variety of perf
trybots, we find that the idle-periods implementation does not have
observable improvement on reducing the negative impact of canvas.toBlob
on the smoothness of animation, even on low-end devices; meanwhile, the
threaded implementation runs canvas.toBlob significantly faster and does
not have the risk of indefinitely delaying the image encoding task like
the idle-periods implementation. Therefore, we decide to switch
canvas.toBlob to its threaded implementation.

This CL will allow people (recipients of intent-to-ship letter) to try out
 canvas.toBlob in its threaded implementation by simply turning on
--enable-experimental-canvas-features flag. Not only that, we also allow
some grace periods to check if the related performance tests on dashboard
have any regression. After approvals from API owners, we will follow with
another CL that completely deletes the idle-periods implementation and
merges the CanvasAsyncBlobCreator back to HTMLCanvasElement to
reduce redundant codes.

BUG=523414

Committed: https://crrev.com/9cbf936a9bc9102b2c9f9a7f6311b53747c2bd52
Cr-Commit-Position: refs/heads/master@{#362787}
==========

[commit-bot: I haz the power, 2015-12-02 20:57:28]

Patchset 2 (id:??) landed as
https://crrev.com/9cbf936a9bc9102b2c9f9a7f6311b53747c2bd52
Cr-Commit-Position: refs/heads/master@{#362787}