(4) Rename files to snake_case: update BUILD.gn, include paths, header guards, and DEPS entries

Mechanically generated by running this command:

tools_webrtc/do-renames.sh update all-renames.txt && git cl format

Then manually updating:

tools_webrtc/sanitizers/tsan_suppressions_webrtc.cc

Bug: webrtc:10159
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: I54824cd91dada8fc3ee3d098f971bc319d477833
Reviewed-on: https://webrtc-review.googlesource.com/c/115653
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26226}
diff --git a/call/BUILD.gn b/call/BUILD.gn
index d457052..6db37a4 100644
--- a/call/BUILD.gn
+++ b/call/BUILD.gn
@@ -191,8 +191,8 @@
 rtc_static_library("call") {
   sources = [
     "call.cc",
-    "callfactory.cc",
-    "callfactory.h",
+    "call_factory.cc",
+    "call_factory.h",
     "degraded_call.cc",
     "degraded_call.h",
     "flexfec_receive_stream_impl.cc",