cc: Delete channel abstraction between proxies.

cc/BUILD.gn

Index: cc/BUILD.gn
diff --git a/cc/BUILD.gn b/cc/BUILD.gn
index 5c13d6ea780e59744ef8534d54a642ba0c8e0943..de99878b796b18a5a3800137bd35ad2250abd534 100644
--- a/cc/BUILD.gn
+++ b/cc/BUILD.gn
@@ -495,8 +495,6 @@ component("cc") {
     "tiles/tiling_set_raster_queue_required.h",
     "trees/blocking_task_runner.cc",
     "trees/blocking_task_runner.h",
-    "trees/channel_impl.h",
-    "trees/channel_main.h",
     "trees/clip_node.cc",
     "trees/clip_node.h",
     "trees/compositor_mode.h",
@@ -559,8 +557,6 @@ component("cc") {
     "trees/target_property.h",
     "trees/task_runner_provider.cc",
     "trees/task_runner_provider.h",
-    "trees/threaded_channel.cc",
-    "trees/threaded_channel.h",
     "trees/transform_node.cc",
     "trees/transform_node.h",
     "trees/tree_synchronizer.cc",
@@ -626,8 +622,6 @@ static_library("test_support") {
     "test/begin_frame_args_test.h",
     "test/begin_frame_source_test.cc",
     "test/begin_frame_source_test.h",
-    "test/fake_channel_impl.cc",
-    "test/fake_channel_impl.h",
     "test/fake_client_picture_cache.cc",
     "test/fake_client_picture_cache.h",
     "test/fake_compositor_frame_sink.cc",