Convert enable_plugins to a buildflag header.

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index f47e36717944a87325137547478112dcdf58ea01..da05c5ff6b54a849cce60518ba0aa959a9fc4018 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -106,6 +106,7 @@
 #include "net/base/net_errors.h"
 #include "net/base/registry_controlled_domains/registry_controlled_domain.h"
 #include "net/http/http_util.h"
+#include "ppapi/features/features.h"
 #include "skia/ext/platform_canvas.h"
 #include "third_party/WebKit/public/platform/FilePathConversion.h"
 #include "third_party/WebKit/public/platform/URLConversion.h"
@@ -187,7 +188,7 @@
 #include "skia/ext/skia_utils_mac.h"
 #endif
 
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
 #include "content/renderer/pepper/pepper_plugin_instance_impl.h"
 #include "content/renderer/pepper/pepper_plugin_registry.h"
 #endif
@@ -1102,7 +1103,7 @@ blink::WebView* RenderViewImpl::webview() const {
   return webview_;
 }
 
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
 
 #if defined(OS_MACOSX)
 void RenderViewImpl::OnGetRenderedText() {