pw_chre: Remove unused files

Remove some utility files that the existing implementation is
not using.

Change-Id: I0a4f80053d6537c2c064e3a13a16f026318a7d66
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/170792
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keir Mierle <keir@google.com>
Commit-Queue: David Gilhooley <dgilhooley@google.com>
diff --git a/third_party/chre/BUILD.gn b/third_party/chre/BUILD.gn
index e5381d9..2833932 100644
--- a/third_party/chre/BUILD.gn
+++ b/third_party/chre/BUILD.gn
@@ -79,14 +79,12 @@
   pw_source_set("shared_platform") {
     public_configs = [ ":disable_warnings" ]
     sources = [
-      "$dir_pw_third_party_chre/platform/shared/assert.cc",
       "$dir_pw_third_party_chre/platform/shared/chre_api_core.cc",
       "$dir_pw_third_party_chre/platform/shared/chre_api_re.cc",
       "$dir_pw_third_party_chre/platform/shared/chre_api_user_settings.cc",
       "$dir_pw_third_party_chre/platform/shared/chre_api_version.cc",
       "$dir_pw_third_party_chre/platform/shared/memory_manager.cc",
       "$dir_pw_third_party_chre/platform/shared/nanoapp/nanoapp_dso_util.cc",
-      "$dir_pw_third_party_chre/platform/shared/pal_system_api.cc",
       "$dir_pw_third_party_chre/platform/shared/system_time.cc",
     ]
 
@@ -122,10 +120,6 @@
       "$dir_pw_third_party_chre/core/timer_pool.cc",
       "$dir_pw_third_party_chre/util/buffer_base.cc",
       "$dir_pw_third_party_chre/util/dynamic_vector_base.cc",
-      "$dir_pw_third_party_chre/util/nanoapp/audio.cc",
-      "$dir_pw_third_party_chre/util/nanoapp/callbacks.cc",
-      "$dir_pw_third_party_chre/util/nanoapp/debug.cc",
-      "$dir_pw_third_party_chre/util/nanoapp/wifi.cc",
       "$dir_pw_third_party_chre/util/system/debug_dump.cc",
     ]