Add a multi-threaded rendering example.

Add a multi-threaded rendering example.

Add a new example to test multi-threaded rendering support to ensure
that the Mozart APIs are not overly thread-hostile.

The Noodles app draws Lissajous figures.  The main thread handles
events and submits SkPictures to the rasterizer thread to be
drawn and composited.

Writing this example provided useful feedback into the design of the
UI helper library and the Scene interface itself, particularly the
separation of event handling from content publishing.

BUG=
R=abarth@google.com

Committed: https://chromium.googlesource.com/external/mojo/+/c8bbaed8e0650d920840b6e79d3cc4c4f040f2e2

[jeffbrown, 2015-12-31 11:21:06]

jeffbrown@google.com changed reviewers:
+ abarth@google.com, jamesr@chromium.org, viettrungluu@chromium.org

[abarth, 2016-01-10 03:25:57]

LGTM

https://codereview.chromium.org/1558813002/diff/1/examples/ui/noodles/noodles...
File examples/ui/noodles/noodles_view.cc (right):

https://codereview.chromium.org/1558813002/diff/1/examples/ui/noodles/noodles...
examples/ui/noodles/noodles_view.cc:27: static void Drop(scoped_ptr<T> ptr) {}
There's a declaration in base for this.  base::Ignored or something like that.

https://codereview.chromium.org/1558813002/diff/1/examples/ui/noodles/noodles...
examples/ui/noodles/noodles_view.cc:107: if
(frame_queue_->PutFrame(std::move(frame))) {
This isn't great for perf, but I guess that's not the point of this example.

https://codereview.chromium.org/1558813002/diff/1/examples/ui/noodles/noodles...
examples/ui/noodles/noodles_view.cc:114: choreographer_.ScheduleDraw();
This should go at the top of the function.

https://codereview.chromium.org/1558813002/diff/1/examples/ui/noodles/noodles...
examples/ui/noodles/noodles_view.cc:119: constexpr int padding = 1;
Why not just const ?

https://codereview.chromium.org/1558813002/diff/1/examples/ui/noodles/noodles...
examples/ui/noodles/noodles_view.cc:147: canvas->flush();
I don't think you need to flush here.  endRecordingAsPicture is basically a
finish.

[jeffbrown, 2016-01-26 08:30:37]

https://codereview.chromium.org/1558813002/diff/1/examples/ui/noodles/noodles...
File examples/ui/noodles/noodles_view.cc (right):

https://codereview.chromium.org/1558813002/diff/1/examples/ui/noodles/noodles...
examples/ui/noodles/noodles_view.cc:27: static void Drop(scoped_ptr<T> ptr) {}
On 2016/01/10 03:25:56, abarth wrote:
> There's a declaration in base for this.  base::Ignored or something like that.

I thought so too but there's only IgnoreResult, not anything to ignore an
argument.

https://codereview.chromium.org/1558813002/diff/1/examples/ui/noodles/noodles...
examples/ui/noodles/noodles_view.cc:107: if
(frame_queue_->PutFrame(std::move(frame))) {
On 2016/01/10 03:25:56, abarth wrote:
> This isn't great for perf, but I guess that's not the point of this example.

Yeah we should really have more backpressure here.

https://codereview.chromium.org/1558813002/diff/1/examples/ui/noodles/noodles...
examples/ui/noodles/noodles_view.cc:114: choreographer_.ScheduleDraw();
On 2016/01/10 03:25:56, abarth wrote:
> This should go at the top of the function.

Done.  Note that Choreographer also contains an optimization to achieve the same
effect by speculatively scheduling one frame ahead.

https://codereview.chromium.org/1558813002/diff/1/examples/ui/noodles/noodles...
examples/ui/noodles/noodles_view.cc:119: constexpr int padding = 1;
On 2016/01/10 03:25:56, abarth wrote:
> Why not just const ?

Eh?  constexpr is my new favorite keyword.  I'll abuse it until I get bored, I
guess.  ;)

https://codereview.chromium.org/1558813002/diff/1/examples/ui/noodles/noodles...
examples/ui/noodles/noodles_view.cc:147: canvas->flush();
On 2016/01/10 03:25:56, abarth wrote:
> I don't think you need to flush here.  endRecordingAsPicture is basically a
> finish.

Removed, here and in other places.

[jeffbrown, 2016-01-26 09:25:21]

address feedback

[jeffbrown, 2016-01-26 23:52:29]

Description was changed from

==========
Add a multi-threaded rendering example.

Add a new example to test multi-threaded rendering support to ensure
that the Mozart APIs are not overly thread-hostile.

The Noodles app draws Lissajous figures.  The main thread handles
events and submits SkPictures to the rasterizer thread to be
drawn and composited.

Writing this example provided useful feedback into the design of the
UI helper library and the Scene interface itself, particularly the
separation of event handling from content publishing.

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

to

==========
Add a multi-threaded rendering example.

Add a new example to test multi-threaded rendering support to ensure
that the Mozart APIs are not overly thread-hostile.

The Noodles app draws Lissajous figures.  The main thread handles
events and submits SkPictures to the rasterizer thread to be
drawn and composited.

Writing this example provided useful feedback into the design of the
UI helper library and the Scene interface itself, particularly the
separation of event handling from content publishing.

BUG=
R=abarth@google.com

Committed:
https://chromium.googlesource.com/external/mojo/+/c8bbaed8e0650d920840b6e79d3...
==========

[jeffbrown, 2016-01-26 23:52:30]

Committed patchset #2 (id:20001) manually as
c8bbaed8e0650d920840b6e79d3cc4c4f040f2e2 (presubmit successful).