Revert "Remove nogncheck and add proper dependencies."

This reverts commit 9b045fa316665fadff25147761fb9a6052db0ccc.

Reason for revert: Pulls opus into data channel only WebRTC

Original change's description:
> Remove nogncheck and add proper dependencies.
> 
> Bug: webrtc:8733
> Change-Id: I7c16f808a07d5f31a6d2a2e62c84b439e835bce1
> Reviewed-on: https://webrtc-review.googlesource.com/40160
> Reviewed-by: Harald Alvestrand <hta@webrtc.org>
> Commit-Queue: Patrik Höglund <phoglund@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#21680}

TBR=phoglund@webrtc.org,hta@webrtc.org

Change-Id: Ice7c3f062c8b112933bde75008e15deb97a48aae
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:8733
Reviewed-on: https://webrtc-review.googlesource.com/41000
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Commit-Queue: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21683}

pc/BUILD.gn

@@ -189,11 +189,8 @@ rtc_static_library("peerconnection") {
     "../call:call_interfaces",
     "../common_video:common_video",
     "../logging:rtc_event_log_api",
-    "../media:rtc_audio_video",
     "../media:rtc_data",
-    "../media:rtc_internal_video_codecs",
     "../media:rtc_media_base",
-    "../modules/audio_device",
     "../p2p:rtc_p2p",
     "../rtc_base:checks",
     "../rtc_base:rtc_base",

pc/channel.cc

@@ -26,6 +26,9 @@
 #include "rtc_base/networkroute.h"
 #include "rtc_base/ptr_util.h"
 #include "rtc_base/trace_event.h"
+// Adding 'nogncheck' to disable the gn include headers check to support modular
+// WebRTC build targets.
+#include "media/engine/webrtcvoiceengine.h"  // nogncheck
 #include "p2p/base/packettransportinternal.h"
 #include "pc/channelmanager.h"
 #include "pc/rtpmediautils.h"

pc/peerconnectionfactory.cc

@@ -25,10 +25,14 @@
 #include "rtc_base/bind.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/ptr_util.h"
-#include "media/engine/webrtcmediaengine.h"
-#include "media/engine/webrtcvideodecoderfactory.h"
-#include "media/engine/webrtcvideoencoderfactory.h"
-#include "modules/audio_device/include/audio_device.h"
+// Adding 'nogncheck' to disable the gn include headers check to support modular
+// WebRTC build targets.
+// TODO(zhihuang): This wouldn't be necessary if the interface and
+// implementation of the media engine were in separate build targets.
+#include "media/engine/webrtcmediaengine.h"             // nogncheck
+#include "media/engine/webrtcvideodecoderfactory.h"     // nogncheck
+#include "media/engine/webrtcvideoencoderfactory.h"     // nogncheck
+#include "modules/audio_device/include/audio_device.h"  // nogncheck
 #include "p2p/base/basicpacketsocketfactory.h"
 #include "p2p/client/basicportallocator.h"
 #include "pc/audiotrack.h"

pc/rtpsender.h

@@ -23,8 +23,9 @@
 #include "api/rtpsenderinterface.h"
 #include "rtc_base/basictypes.h"
 #include "rtc_base/criticalsection.h"
-#include "media/base/audiosource.h"
-#include "pc/channel.h"
+// Adding 'nogncheck' to disable the gn include headers check to support modular
+// WebRTC build targets.
+#include "media/base/audiosource.h"  // nogncheck
 #include "pc/dtmfsender.h"
 #include "pc/statscollector.h"