cc/blimp: Add (de)-serialization for PictureLayer and ScrollbarLayer.

This adds support for serializing these layers from the new code path
and brings us in parity with what the data the existing code serializes.

BUG=648442
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_precise_blink_rel

Review-Url: https://codereview.chromium.org/2397843003
Cr-Commit-Position: refs/heads/master@{#424271}

• cc/BUILD.gn[diff]
• cc/blimp/compositor_state_deserializer.cc[diff]
• cc/blimp/compositor_state_deserializer.h[diff]
• cc/blimp/compositor_state_deserializer_unittest.cc[diff]
• cc/blimp/deserialized_content_layer_client.cc[Added - diff]
• cc/blimp/deserialized_content_layer_client.h[Added - diff]
• cc/blimp/layer_factory.h[diff]
• cc/blimp/layer_tree_host_remote.cc[diff]
• cc/blimp/layer_tree_host_remote.h[diff]
• cc/blimp/layer_tree_host_remote_unittest.cc[diff]
• cc/layers/layer.cc[diff]
• cc/layers/layer.h[diff]
• cc/layers/layer_unittest.cc[diff]
• cc/layers/picture_layer.cc[diff]
• cc/layers/solid_color_scrollbar_layer.cc[diff]
• cc/layers/solid_color_scrollbar_layer.h[diff]
• cc/proto/layer.proto[diff]
• cc/test/remote_client_layer_factory.cc[diff]
• cc/test/remote_client_layer_factory.h[diff]