Move some numeric utility code from rtc_base/ to rtc_base/numerics/

Specifically, I'm moving

  safe_compare.h
  safe_conversions.h
  safe_minmax.h

They shouldn't be part of the API, and moving them to an appropriate
subdirectory of rtc_base/ is a good way to keep track of that.

BUG=webrtc:8445

Change-Id: I458531aeb30bcf4291c4bec3bf22a2fffbf054ff
Reviewed-on: https://webrtc-review.googlesource.com/20860
Commit-Queue: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20829}
diff --git a/api/audio_codecs/L16/audio_decoder_L16.cc b/api/audio_codecs/L16/audio_decoder_L16.cc
index d312f42..dd14e60 100644
--- a/api/audio_codecs/L16/audio_decoder_L16.cc
+++ b/api/audio_codecs/L16/audio_decoder_L16.cc
@@ -13,8 +13,8 @@
 #include "common_types.h"  // NOLINT(build/include)
 #include "modules/audio_coding/codecs/pcm16b/audio_decoder_pcm16b.h"
 #include "modules/audio_coding/codecs/pcm16b/pcm16b_common.h"
+#include "rtc_base/numerics/safe_conversions.h"
 #include "rtc_base/ptr_util.h"
-#include "rtc_base/safe_conversions.h"
 
 namespace webrtc {
 
diff --git a/api/audio_codecs/L16/audio_encoder_L16.cc b/api/audio_codecs/L16/audio_encoder_L16.cc
index 4e14d2d..d0d9f6f 100644
--- a/api/audio_codecs/L16/audio_encoder_L16.cc
+++ b/api/audio_codecs/L16/audio_encoder_L16.cc
@@ -13,8 +13,8 @@
 #include "common_types.h"  // NOLINT(build/include)
 #include "modules/audio_coding/codecs/pcm16b/audio_encoder_pcm16b.h"
 #include "modules/audio_coding/codecs/pcm16b/pcm16b_common.h"
+#include "rtc_base/numerics/safe_conversions.h"
 #include "rtc_base/ptr_util.h"
-#include "rtc_base/safe_conversions.h"
 
 namespace webrtc {
 
diff --git a/api/audio_codecs/g711/audio_decoder_g711.cc b/api/audio_codecs/g711/audio_decoder_g711.cc
index 2191e63..71d363b 100644
--- a/api/audio_codecs/g711/audio_decoder_g711.cc
+++ b/api/audio_codecs/g711/audio_decoder_g711.cc
@@ -15,8 +15,8 @@
 
 #include "common_types.h"  // NOLINT(build/include)
 #include "modules/audio_coding/codecs/g711/audio_decoder_pcm.h"
+#include "rtc_base/numerics/safe_conversions.h"
 #include "rtc_base/ptr_util.h"
-#include "rtc_base/safe_conversions.h"
 
 namespace webrtc {
 
diff --git a/api/audio_codecs/g711/audio_encoder_g711.cc b/api/audio_codecs/g711/audio_encoder_g711.cc
index 0ec8190..7029cae 100644
--- a/api/audio_codecs/g711/audio_encoder_g711.cc
+++ b/api/audio_codecs/g711/audio_encoder_g711.cc
@@ -15,9 +15,9 @@
 
 #include "common_types.h"  // NOLINT(build/include)
 #include "modules/audio_coding/codecs/g711/audio_encoder_pcm.h"
+#include "rtc_base/numerics/safe_conversions.h"
+#include "rtc_base/numerics/safe_minmax.h"
 #include "rtc_base/ptr_util.h"
-#include "rtc_base/safe_conversions.h"
-#include "rtc_base/safe_minmax.h"
 #include "rtc_base/string_to_number.h"
 
 namespace webrtc {
diff --git a/api/audio_codecs/g722/audio_decoder_g722.cc b/api/audio_codecs/g722/audio_decoder_g722.cc
index c50701f..961b126 100644
--- a/api/audio_codecs/g722/audio_decoder_g722.cc
+++ b/api/audio_codecs/g722/audio_decoder_g722.cc
@@ -15,8 +15,8 @@
 
 #include "common_types.h"  // NOLINT(build/include)
 #include "modules/audio_coding/codecs/g722/audio_decoder_g722.h"
+#include "rtc_base/numerics/safe_conversions.h"
 #include "rtc_base/ptr_util.h"
-#include "rtc_base/safe_conversions.h"
 
 namespace webrtc {
 
diff --git a/api/audio_codecs/g722/audio_encoder_g722.cc b/api/audio_codecs/g722/audio_encoder_g722.cc
index c2a70e6..f8aa616 100644
--- a/api/audio_codecs/g722/audio_encoder_g722.cc
+++ b/api/audio_codecs/g722/audio_encoder_g722.cc
@@ -15,9 +15,9 @@
 
 #include "common_types.h"  // NOLINT(build/include)
 #include "modules/audio_coding/codecs/g722/audio_encoder_g722.h"
+#include "rtc_base/numerics/safe_conversions.h"
+#include "rtc_base/numerics/safe_minmax.h"
 #include "rtc_base/ptr_util.h"
-#include "rtc_base/safe_conversions.h"
-#include "rtc_base/safe_minmax.h"
 #include "rtc_base/string_to_number.h"
 
 namespace webrtc {
diff --git a/api/audio_codecs/ilbc/audio_encoder_ilbc.cc b/api/audio_codecs/ilbc/audio_encoder_ilbc.cc
index ab0065e..a7c68ff 100644
--- a/api/audio_codecs/ilbc/audio_encoder_ilbc.cc
+++ b/api/audio_codecs/ilbc/audio_encoder_ilbc.cc
@@ -15,9 +15,9 @@
 
 #include "common_types.h"  // NOLINT(build/include)
 #include "modules/audio_coding/codecs/ilbc/audio_encoder_ilbc.h"
+#include "rtc_base/numerics/safe_conversions.h"
+#include "rtc_base/numerics/safe_minmax.h"
 #include "rtc_base/ptr_util.h"
-#include "rtc_base/safe_conversions.h"
-#include "rtc_base/safe_minmax.h"
 #include "rtc_base/string_to_number.h"
 
 namespace webrtc {
diff --git a/api/video/video_timing.h b/api/video/video_timing.h
index 2271f5d..ab8cd99 100644
--- a/api/video/video_timing.h
+++ b/api/video/video_timing.h
@@ -17,7 +17,7 @@
 #include <string>
 
 #include "rtc_base/checks.h"
-#include "rtc_base/safe_conversions.h"
+#include "rtc_base/numerics/safe_conversions.h"
 
 namespace webrtc {