cc: Split Proxy to eliminate unnecessary dependencies on the impl side

The impl side of the compositor uses Proxy to only access the
task runners and make debug assertions. Move those parts to
TaskRunnerProvider to seperate these dependencies.

BUG=527200
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1411663002

Cr-Commit-Position: refs/heads/master@{#355370}
diff --git a/cc/trees/occlusion_tracker_unittest.cc b/cc/trees/occlusion_tracker_unittest.cc
index dd3c028..680b782a 100644
--- a/cc/trees/occlusion_tracker_unittest.cc
+++ b/cc/trees/occlusion_tracker_unittest.cc
@@ -13,7 +13,7 @@
 #include "cc/output/filter_operation.h"
 #include "cc/output/filter_operations.h"
 #include "cc/test/animation_test_common.h"
-#include "cc/test/fake_impl_proxy.h"
+#include "cc/test/fake_impl_task_runner_provider.h"
 #include "cc/test/fake_layer_tree_host.h"
 #include "cc/test/fake_layer_tree_host_impl.h"
 #include "cc/test/geometry_test_utils.h"