(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/stats/rtc_stats_report_unittest.cc b/stats/rtc_stats_report_unittest.cc
index 80a6f2d..a7d4a42 100644
--- a/stats/rtc_stats_report_unittest.cc
+++ b/stats/rtc_stats_report_unittest.cc
@@ -8,9 +8,9 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include "api/stats/rtcstatsreport.h"
+#include "api/stats/rtc_stats_report.h"
 
-#include "api/stats/rtcstats.h"
+#include "api/stats/rtc_stats.h"
 #include "rtc_base/checks.h"
 #include "test/gtest.h"