Move optional.h to webrtc/api/

We use Optional in our public API, so its header should be in
webrtc/api/.

BUG=webrtc:8205

Review-Url: https://codereview.webrtc.org/3011943002
Cr-Commit-Position: refs/heads/master@{#19693}
diff --git a/webrtc/api/audio_codecs/BUILD.gn b/webrtc/api/audio_codecs/BUILD.gn
index 29238e6..04a5238 100644
--- a/webrtc/api/audio_codecs/BUILD.gn
+++ b/webrtc/api/audio_codecs/BUILD.gn
@@ -27,6 +27,7 @@
   ]
   deps = [
     "..:array_view",
+    "..:optional",
     "../..:webrtc_common",
     "../../rtc_base:rtc_base_approved",
   ]
diff --git a/webrtc/api/audio_codecs/L16/BUILD.gn b/webrtc/api/audio_codecs/L16/BUILD.gn
index db61713..8f06a8f 100644
--- a/webrtc/api/audio_codecs/L16/BUILD.gn
+++ b/webrtc/api/audio_codecs/L16/BUILD.gn
@@ -19,6 +19,7 @@
   ]
   deps = [
     "..:audio_codecs_api",
+    "../..:optional",
     "../../..:webrtc_common",
     "../../../modules/audio_coding:pcm16b",
     "../../../rtc_base:rtc_base_approved",
@@ -32,6 +33,7 @@
   ]
   deps = [
     "..:audio_codecs_api",
+    "../..:optional",
     "../../..:webrtc_common",
     "../../../modules/audio_coding:pcm16b",
     "../../../rtc_base:rtc_base_approved",
diff --git a/webrtc/api/audio_codecs/L16/audio_decoder_L16.h b/webrtc/api/audio_codecs/L16/audio_decoder_L16.h
index 478da16..39b389a 100644
--- a/webrtc/api/audio_codecs/L16/audio_decoder_L16.h
+++ b/webrtc/api/audio_codecs/L16/audio_decoder_L16.h
@@ -16,7 +16,7 @@
 
 #include "webrtc/api/audio_codecs/audio_decoder.h"
 #include "webrtc/api/audio_codecs/audio_format.h"
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
diff --git a/webrtc/api/audio_codecs/L16/audio_encoder_L16.h b/webrtc/api/audio_codecs/L16/audio_encoder_L16.h
index e2e4019..3ac0423 100644
--- a/webrtc/api/audio_codecs/L16/audio_encoder_L16.h
+++ b/webrtc/api/audio_codecs/L16/audio_encoder_L16.h
@@ -16,7 +16,7 @@
 
 #include "webrtc/api/audio_codecs/audio_encoder.h"
 #include "webrtc/api/audio_codecs/audio_format.h"
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
diff --git a/webrtc/api/audio_codecs/audio_decoder.h b/webrtc/api/audio_codecs/audio_decoder.h
index 0d15e6d..2d850fd 100644
--- a/webrtc/api/audio_codecs/audio_decoder.h
+++ b/webrtc/api/audio_codecs/audio_decoder.h
@@ -15,9 +15,9 @@
 #include <vector>
 
 #include "webrtc/api/array_view.h"
+#include "webrtc/api/optional.h"
 #include "webrtc/rtc_base/buffer.h"
 #include "webrtc/rtc_base/constructormagic.h"
-#include "webrtc/rtc_base/optional.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
diff --git a/webrtc/api/audio_codecs/audio_encoder.h b/webrtc/api/audio_codecs/audio_encoder.h
index 37a03d0..7406d7d 100644
--- a/webrtc/api/audio_codecs/audio_encoder.h
+++ b/webrtc/api/audio_codecs/audio_encoder.h
@@ -17,9 +17,9 @@
 #include <vector>
 
 #include "webrtc/api/array_view.h"
+#include "webrtc/api/optional.h"
 #include "webrtc/rtc_base/buffer.h"
 #include "webrtc/rtc_base/deprecation.h"
-#include "webrtc/rtc_base/optional.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
diff --git a/webrtc/api/audio_codecs/audio_format.h b/webrtc/api/audio_codecs/audio_format.h
index c442972..ab825bb 100644
--- a/webrtc/api/audio_codecs/audio_format.h
+++ b/webrtc/api/audio_codecs/audio_format.h
@@ -16,7 +16,7 @@
 #include <string>
 #include <utility>
 
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
diff --git a/webrtc/api/audio_codecs/g711/BUILD.gn b/webrtc/api/audio_codecs/g711/BUILD.gn
index fbf9248..aa86490 100644
--- a/webrtc/api/audio_codecs/g711/BUILD.gn
+++ b/webrtc/api/audio_codecs/g711/BUILD.gn
@@ -19,6 +19,7 @@
   ]
   deps = [
     "..:audio_codecs_api",
+    "../..:optional",
     "../../..:webrtc_common",
     "../../../modules/audio_coding:g711",
     "../../../rtc_base:rtc_base_approved",
@@ -32,6 +33,7 @@
   ]
   deps = [
     "..:audio_codecs_api",
+    "../..:optional",
     "../../..:webrtc_common",
     "../../../modules/audio_coding:g711",
     "../../../rtc_base:rtc_base_approved",
diff --git a/webrtc/api/audio_codecs/g711/audio_decoder_g711.h b/webrtc/api/audio_codecs/g711/audio_decoder_g711.h
index b9650c9..2824c32 100644
--- a/webrtc/api/audio_codecs/g711/audio_decoder_g711.h
+++ b/webrtc/api/audio_codecs/g711/audio_decoder_g711.h
@@ -16,7 +16,7 @@
 
 #include "webrtc/api/audio_codecs/audio_decoder.h"
 #include "webrtc/api/audio_codecs/audio_format.h"
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
diff --git a/webrtc/api/audio_codecs/g711/audio_encoder_g711.h b/webrtc/api/audio_codecs/g711/audio_encoder_g711.h
index a22650d..5750100 100644
--- a/webrtc/api/audio_codecs/g711/audio_encoder_g711.h
+++ b/webrtc/api/audio_codecs/g711/audio_encoder_g711.h
@@ -16,7 +16,7 @@
 
 #include "webrtc/api/audio_codecs/audio_encoder.h"
 #include "webrtc/api/audio_codecs/audio_format.h"
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
diff --git a/webrtc/api/audio_codecs/g722/BUILD.gn b/webrtc/api/audio_codecs/g722/BUILD.gn
index f3108e7..5af7e5c 100644
--- a/webrtc/api/audio_codecs/g722/BUILD.gn
+++ b/webrtc/api/audio_codecs/g722/BUILD.gn
@@ -26,6 +26,7 @@
   deps = [
     ":audio_encoder_g722_config",
     "..:audio_codecs_api",
+    "../..:optional",
     "../../..:webrtc_common",
     "../../../modules/audio_coding:g722",
     "../../../rtc_base:rtc_base_approved",
@@ -39,6 +40,7 @@
   ]
   deps = [
     "..:audio_codecs_api",
+    "../..:optional",
     "../../..:webrtc_common",
     "../../../modules/audio_coding:g722",
     "../../../rtc_base:rtc_base_approved",
diff --git a/webrtc/api/audio_codecs/g722/audio_decoder_g722.h b/webrtc/api/audio_codecs/g722/audio_decoder_g722.h
index 9b063c2..cf0dfa9 100644
--- a/webrtc/api/audio_codecs/g722/audio_decoder_g722.h
+++ b/webrtc/api/audio_codecs/g722/audio_decoder_g722.h
@@ -16,7 +16,7 @@
 
 #include "webrtc/api/audio_codecs/audio_decoder.h"
 #include "webrtc/api/audio_codecs/audio_format.h"
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
diff --git a/webrtc/api/audio_codecs/g722/audio_encoder_g722.h b/webrtc/api/audio_codecs/g722/audio_encoder_g722.h
index 458a6c5..37cb968 100644
--- a/webrtc/api/audio_codecs/g722/audio_encoder_g722.h
+++ b/webrtc/api/audio_codecs/g722/audio_encoder_g722.h
@@ -17,7 +17,7 @@
 #include "webrtc/api/audio_codecs/audio_encoder.h"
 #include "webrtc/api/audio_codecs/audio_format.h"
 #include "webrtc/api/audio_codecs/g722/audio_encoder_g722_config.h"
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
diff --git a/webrtc/api/audio_codecs/ilbc/BUILD.gn b/webrtc/api/audio_codecs/ilbc/BUILD.gn
index ab9681a..0f5f80d 100644
--- a/webrtc/api/audio_codecs/ilbc/BUILD.gn
+++ b/webrtc/api/audio_codecs/ilbc/BUILD.gn
@@ -26,6 +26,7 @@
   deps = [
     ":audio_encoder_ilbc_config",
     "..:audio_codecs_api",
+    "../..:optional",
     "../../..:webrtc_common",
     "../../../modules/audio_coding:ilbc",
     "../../../rtc_base:rtc_base_approved",
@@ -39,6 +40,7 @@
   ]
   deps = [
     "..:audio_codecs_api",
+    "../..:optional",
     "../../..:webrtc_common",
     "../../../modules/audio_coding:ilbc",
     "../../../rtc_base:rtc_base_approved",
diff --git a/webrtc/api/audio_codecs/ilbc/audio_decoder_ilbc.h b/webrtc/api/audio_codecs/ilbc/audio_decoder_ilbc.h
index 65a67e2..343308d 100644
--- a/webrtc/api/audio_codecs/ilbc/audio_decoder_ilbc.h
+++ b/webrtc/api/audio_codecs/ilbc/audio_decoder_ilbc.h
@@ -16,7 +16,7 @@
 
 #include "webrtc/api/audio_codecs/audio_decoder.h"
 #include "webrtc/api/audio_codecs/audio_format.h"
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
diff --git a/webrtc/api/audio_codecs/ilbc/audio_encoder_ilbc.h b/webrtc/api/audio_codecs/ilbc/audio_encoder_ilbc.h
index 6f7a9f6..a30d109 100644
--- a/webrtc/api/audio_codecs/ilbc/audio_encoder_ilbc.h
+++ b/webrtc/api/audio_codecs/ilbc/audio_encoder_ilbc.h
@@ -17,7 +17,7 @@
 #include "webrtc/api/audio_codecs/audio_encoder.h"
 #include "webrtc/api/audio_codecs/audio_format.h"
 #include "webrtc/api/audio_codecs/ilbc/audio_encoder_ilbc_config.h"
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
diff --git a/webrtc/api/audio_codecs/isac/BUILD.gn b/webrtc/api/audio_codecs/isac/BUILD.gn
index 3340e28..b22eb95 100644
--- a/webrtc/api/audio_codecs/isac/BUILD.gn
+++ b/webrtc/api/audio_codecs/isac/BUILD.gn
@@ -19,6 +19,7 @@
   ]
   deps = [
     "..:audio_codecs_api",
+    "../..:optional",
     "../../..:webrtc_common",
     "../../../modules/audio_coding:isac_fix",
     "../../../rtc_base:rtc_base_approved",
@@ -32,6 +33,7 @@
   ]
   deps = [
     "..:audio_codecs_api",
+    "../..:optional",
     "../../..:webrtc_common",
     "../../../modules/audio_coding:isac_fix",
     "../../../rtc_base:rtc_base_approved",
@@ -45,6 +47,7 @@
   ]
   deps = [
     "..:audio_codecs_api",
+    "../..:optional",
     "../../..:webrtc_common",
     "../../../modules/audio_coding:isac",
     "../../../rtc_base:rtc_base_approved",
@@ -58,6 +61,7 @@
   ]
   deps = [
     "..:audio_codecs_api",
+    "../..:optional",
     "../../..:webrtc_common",
     "../../../modules/audio_coding:isac",
     "../../../rtc_base:rtc_base_approved",
diff --git a/webrtc/api/audio_codecs/isac/audio_decoder_isac_fix.h b/webrtc/api/audio_codecs/isac/audio_decoder_isac_fix.h
index 71e7cc4..7662002 100644
--- a/webrtc/api/audio_codecs/isac/audio_decoder_isac_fix.h
+++ b/webrtc/api/audio_codecs/isac/audio_decoder_isac_fix.h
@@ -16,7 +16,7 @@
 
 #include "webrtc/api/audio_codecs/audio_decoder.h"
 #include "webrtc/api/audio_codecs/audio_format.h"
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
diff --git a/webrtc/api/audio_codecs/isac/audio_decoder_isac_float.h b/webrtc/api/audio_codecs/isac/audio_decoder_isac_float.h
index c0dc880..f0232e9 100644
--- a/webrtc/api/audio_codecs/isac/audio_decoder_isac_float.h
+++ b/webrtc/api/audio_codecs/isac/audio_decoder_isac_float.h
@@ -16,7 +16,7 @@
 
 #include "webrtc/api/audio_codecs/audio_decoder.h"
 #include "webrtc/api/audio_codecs/audio_format.h"
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
diff --git a/webrtc/api/audio_codecs/isac/audio_encoder_isac_fix.h b/webrtc/api/audio_codecs/isac/audio_encoder_isac_fix.h
index 5f0e8fe..ce4a1d0 100644
--- a/webrtc/api/audio_codecs/isac/audio_encoder_isac_fix.h
+++ b/webrtc/api/audio_codecs/isac/audio_encoder_isac_fix.h
@@ -16,7 +16,7 @@
 
 #include "webrtc/api/audio_codecs/audio_encoder.h"
 #include "webrtc/api/audio_codecs/audio_format.h"
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
diff --git a/webrtc/api/audio_codecs/isac/audio_encoder_isac_float.h b/webrtc/api/audio_codecs/isac/audio_encoder_isac_float.h
index 35bc94b..244e59b 100644
--- a/webrtc/api/audio_codecs/isac/audio_encoder_isac_float.h
+++ b/webrtc/api/audio_codecs/isac/audio_encoder_isac_float.h
@@ -16,7 +16,7 @@
 
 #include "webrtc/api/audio_codecs/audio_encoder.h"
 #include "webrtc/api/audio_codecs/audio_format.h"
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
diff --git a/webrtc/api/audio_codecs/opus/BUILD.gn b/webrtc/api/audio_codecs/opus/BUILD.gn
index 658d151..faa5956 100644
--- a/webrtc/api/audio_codecs/opus/BUILD.gn
+++ b/webrtc/api/audio_codecs/opus/BUILD.gn
@@ -18,6 +18,7 @@
     "audio_encoder_opus_config.h",
   ]
   deps = [
+    "../..:optional",
     "../../../rtc_base:rtc_base_approved",
   ]
   defines = []
@@ -51,6 +52,7 @@
   ]
   deps = [
     "..:audio_codecs_api",
+    "../..:optional",
     "../../..:webrtc_common",
     "../../../modules/audio_coding:webrtc_opus",
     "../../../rtc_base:rtc_base_approved",
diff --git a/webrtc/api/audio_codecs/opus/audio_decoder_opus.h b/webrtc/api/audio_codecs/opus/audio_decoder_opus.h
index 6a9d6da..272503d 100644
--- a/webrtc/api/audio_codecs/opus/audio_decoder_opus.h
+++ b/webrtc/api/audio_codecs/opus/audio_decoder_opus.h
@@ -16,7 +16,7 @@
 
 #include "webrtc/api/audio_codecs/audio_decoder.h"
 #include "webrtc/api/audio_codecs/audio_format.h"
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {
 
diff --git a/webrtc/api/audio_codecs/opus/audio_encoder_opus_config.h b/webrtc/api/audio_codecs/opus/audio_encoder_opus_config.h
index c3fe17b..d07f784 100644
--- a/webrtc/api/audio_codecs/opus/audio_encoder_opus_config.h
+++ b/webrtc/api/audio_codecs/opus/audio_encoder_opus_config.h
@@ -15,7 +15,7 @@
 
 #include <vector>
 
-#include "webrtc/rtc_base/optional.h"
+#include "webrtc/api/optional.h"
 
 namespace webrtc {