cc: Implement tiling iterator based on pyramid sequence.

cc: Implement tiling iterator based on pyramid sequence.

This patch implements pyramid sequence for getting tile indices from
closer to farther or farther to closer fashion. The pyramid sequence
iterates level by level, i.e. inner level to outer level and vice
versa. This is used to implement SpiralDifferenceIterator and
ReverseSpiralDifferenceIterator. The pyramid sequence takes width and
height of the tile into consideration, giving better order of tiles
over previous version.

The tiling iterator can be specified to use pyramid sequence by using
"--tiling-iterator=pyramid-sequence". By default tiling iterator
is spiral iterator.

BUG=613695
TESTS=PyramidSequenceTest.*
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

[prashant.n, 2016-11-15 13:57:41]

Description was changed from

==========
cc: Implement tiling iterator based on pyramid sequence.

This patch implements pyramid sequence for getting tile indices from
closer to farther or farther to closer fashion. The pyramid sequence
iterates level by level, i.e. inner level to outer level and vice
versa. This is used to implement SpiralDifferenceIterator and
ReverseSpiralDifferenceIterator. The pyramid sequence takes width and
height of the tile into consideration, giving better order of tiles
over previous version.

The tiling iterator can be specified to use pyramid sequence by using
"--tiling-iterator=pyramid-sequence". By default tiling iterator
is spiral iterator.

BUG=613695
TESTS=PyramidSequenceTest.*
==========

to

==========
cc: Implement tiling iterator based on pyramid sequence.

This patch implements pyramid sequence for getting tile indices from
closer to farther or farther to closer fashion. The pyramid sequence
iterates level by level, i.e. inner level to outer level and vice
versa. This is used to implement SpiralDifferenceIterator and
ReverseSpiralDifferenceIterator. The pyramid sequence takes width and
height of the tile into consideration, giving better order of tiles
over previous version.

The tiling iterator can be specified to use pyramid sequence by using
"--tiling-iterator=pyramid-sequence". By default tiling iterator
is spiral iterator.

BUG=613695
TESTS=PyramidSequenceTest.*
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel
==========

[prashant.n, 2016-11-15 13:59:29]

prashant.n@samsung.com changed reviewers:
+ enne@chromium.org, vmpstr@chromium.org

[prashant.n, 2016-11-15 13:59:29]

ptal.

[prashant.n, 2016-11-22 06:27:02]

I'll try to make this faster than current spiral iterator.