cc: Refactor TileTaskWorkerPool.

This patch moves tile task management from all TileTaskWorkerPool
classes to separate class making them thinner.

New class TileTaskManager now handles running tasks using task graph
runner set. This now puts the logic of raster buffer provider and
running task in different classes. This patch also renames all
TileTaskWorkerPools to RasterBufferProviders to depict what they
really do. New test classes FakeRasterBufferProviderImpl,
FakeTileTaskManagerImpl are added to cut the duplicated code.

Fixed duplicate nodes getting added in task graph in raster buffer
provider perftests.

BUG=599863
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review-Url: https://codereview.chromium.org/1910213005
Cr-Commit-Position: refs/heads/master@{#390632}
43 files changed