Convert spellcheck to a buildflag header.

chrome/renderer/chrome_content_renderer_client.h

Index: chrome/renderer/chrome_content_renderer_client.h
diff --git a/chrome/renderer/chrome_content_renderer_client.h b/chrome/renderer/chrome_content_renderer_client.h
index 1cf88d918ffb2c870e2eeeb514d329811a6d0de1..4f7bbbbc2eed67563eea118cd95dd09fc8a3a1f9 100644
--- a/chrome/renderer/chrome_content_renderer_client.h
+++ b/chrome/renderer/chrome_content_renderer_client.h
@@ -17,6 +17,7 @@
 #include "base/gtest_prod_util.h"
 #include "base/strings/string16.h"
 #include "components/rappor/public/interfaces/rappor_recorder.mojom.h"
+#include "components/spellcheck/spellcheck_build_features.h"
 #include "content/public/renderer/content_renderer_client.h"
 #include "extensions/features/features.h"
 #include "ipc/ipc_channel_proxy.h"
@@ -32,7 +33,7 @@ class ChromeRenderThreadObserver;
 class ChromePDFPrintClient;
 #endif
 class PrescientNetworkingDispatcher;
-#if defined(ENABLE_SPELLCHECK)
+#if BUILDFLAG(ENABLE_SPELLCHECK)
 class SpellCheck;
 class SpellCheckProvider;
 #endif
@@ -186,7 +187,7 @@ class ChromeContentRendererClient : public content::ContentRendererClient {
   bool ShouldEnforceWebRTCRoutingPreferences() override;
   GURL OverrideFlashEmbedWithHTML(const GURL& url) override;
 
-#if defined(ENABLE_SPELLCHECK)
+#if BUILDFLAG(ENABLE_SPELLCHECK)
   // Sets a new |spellcheck|. Used for testing only.
   // Takes ownership of |spellcheck|.
   void SetSpellcheck(SpellCheck* spellcheck);
@@ -235,7 +236,7 @@ class ChromeContentRendererClient : public content::ContentRendererClient {
   std::unique_ptr<network_hints::PrescientNetworkingDispatcher>
       prescient_networking_dispatcher_;
 
-#if defined(ENABLE_SPELLCHECK)
+#if BUILDFLAG(ENABLE_SPELLCHECK)
   std::unique_ptr<SpellCheck> spellcheck_;
 #endif
   std::unique_ptr<safe_browsing::PhishingClassifierFilter> phishing_classifier_;