cc: Remove dead code.

Delete some TilePriority-related dead debug code.

BUG=none

Change-Id: Ia1a9fa25c6bf2fa9546084a56291c9c3574a20f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2231508
Commit-Queue: vmpstr <vmpstr@chromium.org>
Auto-Submit: Sadrul Chowdhury <sadrul@chromium.org>
Reviewed-by: vmpstr <vmpstr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776067}

cc/tiles/tile_priority.cc

@@ -11,18 +11,6 @@
 
 namespace cc {
 
-std::string WhichTreeToString(WhichTree tree) {
-  switch (tree) {
-  case ACTIVE_TREE:
-    return "ACTIVE_TREE";
-  case PENDING_TREE:
-    return "PENDING_TREE";
-  default:
-      DCHECK(false) << "Unrecognized WhichTree value " << tree;
-      return "<unknown WhichTree value>";
-  }
-}
-
 std::string TileResolutionToString(TileResolution resolution) {
   switch (resolution) {
   case LOW_RESOLUTION:

cc/tiles/tile_priority.h

@@ -16,10 +16,6 @@
 #include "cc/cc_export.h"
 #include "third_party/perfetto/protos/perfetto/trace/track_event/chrome_compositor_scheduler_state.pbzero.h"
 
-namespace base {
-class Value;
-}
-
 namespace cc {
 
 enum WhichTree {
@@ -28,9 +24,7 @@ enum WhichTree {
   ACTIVE_TREE = 0,
   PENDING_TREE = 1,
   LAST_TREE = 1
-  // Be sure to update WhichTreeAsValue when adding new fields.
 };
-std::unique_ptr<base::Value> WhichTreeAsValue(WhichTree tree);
 
 enum TileResolution {
   LOW_RESOLUTION = 0 ,