AW: Improve code health for SpellCheck

The CL:
1. Add BUILDFLAG::ENABLE_SPELLCHECK in aw_main_delegate.cc
2. Remove redundant include spellcheck_build_features.h

Bug: None
Change-Id: Idc77171292fd0515240e52d86ac83fbdb4744534
Reviewed-on: https://chromium-review.googlesource.com/939221Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: Bo <boliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539448}

android_webview/lib/aw_main_delegate.cc

@@ -34,7 +34,7 @@
 #include "components/crash/content/app/breakpad_linux.h"
 #include "components/crash/core/common/crash_key.h"
 #include "components/safe_browsing/android/safe_browsing_api_handler_bridge.h"
-#include "components/spellcheck/common/spellcheck_features.h"
+#include "components/spellcheck/spellcheck_build_features.h"
 #include "content/public/browser/android/browser_media_player_manager_register.h"
 #include "content/public/browser/browser_main_runner.h"
 #include "content/public/browser/browser_thread.h"
@@ -51,6 +51,10 @@
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/events/gesture_detection/gesture_configuration.h"
 
+#if BUILDFLAG(ENABLE_SPELLCHECK)
+#include "components/spellcheck/common/spellcheck_features.h"
+#endif  // ENABLE_SPELLCHECK
+
 namespace android_webview {
 
 AwMainDelegate::AwMainDelegate() {}
@@ -144,8 +148,10 @@ bool AwMainDelegate::BasicStartupComplete(int* exit_code) {
     cl->AppendSwitch(switches::kInProcessGPU);
   }
 
+#if BUILDFLAG(ENABLE_SPELLCHECK)
   CommandLineHelper::AddEnabledFeature(
       *cl, spellcheck::kAndroidSpellCheckerNonLowEnd.name);
+#endif  // ENABLE_SPELLCHECK
 
   CommandLineHelper::AddDisabledFeature(*cl, features::kWebPayments.name);
 

android_webview/renderer/aw_content_renderer_client.cc

@@ -27,7 +27,6 @@
 #include "base/strings/utf_string_conversions.h"
 #include "components/printing/renderer/print_render_frame_helper.h"
 #include "components/safe_browsing/renderer/websocket_sb_handshake_throttle.h"
-#include "components/spellcheck/spellcheck_build_features.h"
 #include "components/supervised_user_error_page/gin_wrapper.h"
 #include "components/supervised_user_error_page/supervised_user_error_page_android.h"
 #include "components/visitedlink/renderer/visitedlink_slave.h"