Move enable_webrtc to a buildflag header.

content/public/test/mock_render_process_host.cc

Index: content/public/test/mock_render_process_host.cc
diff --git a/content/public/test/mock_render_process_host.cc b/content/public/test/mock_render_process_host.cc
index c06587785b19897f094d41a5212a3239fbbce561..e9fb8e9bf608cb0c3a53a543f3e57a3e6348f6de 100644
--- a/content/public/test/mock_render_process_host.cc
+++ b/content/public/test/mock_render_process_host.cc
@@ -29,6 +29,7 @@
 #include "content/public/browser/notification_types.h"
 #include "content/public/browser/render_widget_host_iterator.h"
 #include "content/public/browser/storage_partition.h"
+#include "media/media_features.h"
 #include "mojo/public/cpp/bindings/associated_interface_ptr.h"
 
 namespace content {
@@ -314,7 +315,7 @@ void MockRenderProcessHost::FilterURL(bool empty_allowed, GURL* url) {
   RenderProcessHostImpl::FilterURL(this, empty_allowed, url);
 }
 
-#if defined(ENABLE_WEBRTC)
+#if BUILDFLAG(ENABLE_WEBRTC)
 void MockRenderProcessHost::EnableAudioDebugRecordings(
     const base::FilePath& file) {
 }