Move enable_webrtc to a buildflag header.

content/renderer/renderer_main.cc

Index: content/renderer/renderer_main.cc
diff --git a/content/renderer/renderer_main.cc b/content/renderer/renderer_main.cc
index e356a096a5fea582240f747261681a64560b59e5..8fa4c828119be6770613f807fa4a4932e2c1b3ae 100644
--- a/content/renderer/renderer_main.cc
+++ b/content/renderer/renderer_main.cc
@@ -30,6 +30,7 @@
 #include "content/renderer/render_process_impl.h"
 #include "content/renderer/render_thread_impl.h"
 #include "content/renderer/renderer_main_platform_delegate.h"
+#include "media/media_features.h"
 #include "ppapi/features/features.h"
 #include "third_party/WebKit/public/platform/scheduler/renderer/renderer_scheduler.h"
 #include "third_party/skia/include/core/SkGraphics.h"
@@ -53,7 +54,7 @@
 #include "content/renderer/pepper/pepper_plugin_registry.h"
 #endif
 
-#if defined(ENABLE_WEBRTC)
+#if BUILDFLAG(ENABLE_WEBRTC)
 #include "third_party/webrtc_overrides/init_webrtc.h"
 #endif
 
@@ -163,7 +164,7 @@ int RendererMain(const MainFunctionParams& parameters) {
   // Load pepper plugins before engaging the sandbox.
   PepperPluginRegistry::GetInstance();
 #endif
-#if defined(ENABLE_WEBRTC)
+#if BUILDFLAG(ENABLE_WEBRTC)
   // Initialize WebRTC before engaging the sandbox.
   // NOTE: On linux, this call could already have been made from
   // zygote_main_linux.cc.  However, calling multiple times from the same thread