Move enable_webrtc to a buildflag header.

chrome/renderer/chrome_content_renderer_client.cc

Index: chrome/renderer/chrome_content_renderer_client.cc
diff --git a/chrome/renderer/chrome_content_renderer_client.cc b/chrome/renderer/chrome_content_renderer_client.cc
index 17c0a056c7ccfbb57341f55d6cfef09574b2814a..d5322e3b44dfbe340c119535395a253d13a0dd31 100644
--- a/chrome/renderer/chrome_content_renderer_client.cc
+++ b/chrome/renderer/chrome_content_renderer_client.cc
@@ -94,6 +94,7 @@
 #include "extensions/common/constants.h"
 #include "extensions/features/features.h"
 #include "ipc/ipc_sync_channel.h"
+#include "media/media_features.h"
 #include "net/base/net_errors.h"
 #include "ppapi/c/private/ppb_pdf.h"
 #include "ppapi/features/features.h"
@@ -159,7 +160,7 @@
 #include "components/spellcheck/renderer/spellcheck_provider.h"
 #endif
 
-#if defined(ENABLE_WEBRTC)
+#if BUILDFLAG(ENABLE_WEBRTC)
 #include "chrome/renderer/media/webrtc_logging_message_filter.h"
 #endif
 
@@ -351,7 +352,7 @@ void ChromeContentRendererClient::RenderThreadStarted() {
   prerender_dispatcher_.reset(new prerender::PrerenderDispatcher());
   subresource_filter_ruleset_dealer_.reset(
       new subresource_filter::RulesetDealer());
-#if defined(ENABLE_WEBRTC)
+#if BUILDFLAG(ENABLE_WEBRTC)
   webrtc_logging_message_filter_ =
       new WebRtcLoggingMessageFilter(thread->GetIOTaskRunner());
 #endif
@@ -364,7 +365,7 @@ void ChromeContentRendererClient::RenderThreadStarted() {
   thread->AddObserver(subresource_filter_ruleset_dealer_.get());
   thread->AddObserver(SearchBouncer::GetInstance());
 
-#if defined(ENABLE_WEBRTC)
+#if BUILDFLAG(ENABLE_WEBRTC)
   thread->AddFilter(webrtc_logging_message_filter_.get());
 #endif