Convert enable_plugins to a buildflag header.

content/shell/renderer/shell_content_renderer_client.cc

Index: content/shell/renderer/shell_content_renderer_client.cc
diff --git a/content/shell/renderer/shell_content_renderer_client.cc b/content/shell/renderer/shell_content_renderer_client.cc
index 3fe337de8a84e9dfb8b12664d08bf74eb45fc543..2fd5d5c2a95b9e9d930912c5e03e86bcbcfa6035 100644
--- a/content/shell/renderer/shell_content_renderer_client.cc
+++ b/content/shell/renderer/shell_content_renderer_client.cc
@@ -17,12 +17,13 @@
 #include "content/shell/renderer/shell_render_view_observer.h"
 #include "mojo/public/cpp/bindings/binding.h"
 #include "mojo/public/cpp/system/message_pipe.h"
+#include "ppapi/features/features.h"
 #include "services/service_manager/public/cpp/interface_registry.h"
 #include "third_party/WebKit/public/web/WebTestingSupport.h"
 #include "third_party/WebKit/public/web/WebView.h"
 #include "v8/include/v8.h"
 
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
 #include "ppapi/shared_impl/ppapi_switches.h"
 #endif
 
@@ -109,7 +110,7 @@ void ShellContentRendererClient::RenderViewCreated(RenderView* render_view) {
 
 bool ShellContentRendererClient::IsPluginAllowedToUseCompositorAPI(
     const GURL& url) {
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
   return base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kEnablePepperTesting);
 #else
@@ -118,7 +119,7 @@ bool ShellContentRendererClient::IsPluginAllowedToUseCompositorAPI(
 }
 
 bool ShellContentRendererClient::IsPluginAllowedToUseDevChannelAPIs() {
-#if defined(ENABLE_PLUGINS)
+#if BUILDFLAG(ENABLE_PLUGINS)
   return base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kEnablePepperTesting);
 #else