cc: Separate ImageDecodeController into software and gpu parts.

This patch separates ImageDecodeController into the software and gpu
components, which are created when tile manager resources are set.

This allows independent development of the two paths without extra
complications involved trying to handle both cases in the same class.

R=enne, ericrk
BUG=581423
CQ_EXTRA_TRYBOTS=tryserver.blink:linux_blink_rel
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1642803003

Cr-Commit-Position: refs/heads/master@{#378895}

diff --git a/cc/BUILD.gn b/cc/BUILD.gn
index 023c7ba..6650bb5 100644
--- a/cc/BUILD.gn
+++ b/cc/BUILD.gn

@@ -444,7 +444,8 @@
     "scheduler/video_frame_controller.h",
     "tiles/eviction_tile_priority_queue.cc",
     "tiles/eviction_tile_priority_queue.h",
-    "tiles/image_decode_controller.cc",
+    "tiles/gpu_image_decode_controller.cc",
+    "tiles/gpu_image_decode_controller.h",
     "tiles/image_decode_controller.h",
     "tiles/picture_layer_tiling.cc",
     "tiles/picture_layer_tiling.h",
@@ -458,6 +459,8 @@
     "tiles/raster_tile_priority_queue_all.h",
     "tiles/raster_tile_priority_queue_required.cc",
     "tiles/raster_tile_priority_queue_required.h",
+    "tiles/software_image_decode_controller.cc",
+    "tiles/software_image_decode_controller.h",
     "tiles/tile.cc",
     "tiles/tile.h",
     "tiles/tile_draw_info.cc",
@@ -862,9 +865,9 @@
     "test/mock_helper_unittest.cc",
     "test/ordered_simple_task_runner_unittest.cc",
     "test/test_web_graphics_context_3d_unittest.cc",
-    "tiles/image_decode_controller_unittest.cc",
     "tiles/picture_layer_tiling_set_unittest.cc",
     "tiles/picture_layer_tiling_unittest.cc",
+    "tiles/software_image_decode_controller_unittest.cc",
     "tiles/tile_manager_unittest.cc",
     "tiles/tile_priority_unittest.cc",
     "trees/blocking_task_runner_unittest.cc",