cc: Block drawing of tiles without twins.

cc: Block drawing of tiles without twins.

When there is a race between activation+drawing and rasterizing,
for tiles without twins, we should prevent the active tree from
drawing these tiles.

BUG=

[sohanjg, 2014-09-08 10:08:04]

sohan.jyoti@samsung.com changed reviewers:
+ danakj@chromium.org

[sohanjg, 2014-09-08 10:08:05]

Can you please take a look, thanks!

[sohanjg, 2014-09-08 13:45:16]

https://codereview.chromium.org/548223003/diff/1/cc/layers/picture_layer_impl.cc
File cc/layers/picture_layer_impl.cc (right):

https://codereview.chromium.org/548223003/diff/1/cc/layers/picture_layer_impl...
cc/layers/picture_layer_impl.cc:874:
layer_tree_impl()->SetRequiresHighResToDraw();
we should SetRequiresHighResToDraw, on the twin layer impl tree i think, but
that causes couple of tests *.NothingRequiredIfActiveMissingTiles fails, i am
checking them.

Also, will this be right place to block draw ?

[sohanjg, 2014-09-08 15:17:32]

https://codereview.chromium.org/548223003/diff/1/cc/trees/layer_tree_host_uni...
File cc/trees/layer_tree_host_unittest_context.cc (right):

https://codereview.chromium.org/548223003/diff/1/cc/trees/layer_tree_host_uni...
cc/trees/layer_tree_host_unittest_context.cc:334: 
Are we drawing/recording this too far away from visible rect, that we dont make
twin tile for it ?

[sohanjg, 2014-09-09 09:21:01]

We will track it as part of https://codereview.chromium.org/475633008/