gn BUILD fixes for disabling enable_extensions and use_ash feature flags.

chrome/browser/devtools/BUILD.gn

Index: chrome/browser/devtools/BUILD.gn
diff --git a/chrome/browser/devtools/BUILD.gn b/chrome/browser/devtools/BUILD.gn
index 55ef983a1ed22b77107c6d544002f1cb16692d7d..c560e188fab40779ed48906368081e09db53d737 100644
--- a/chrome/browser/devtools/BUILD.gn
+++ b/chrome/browser/devtools/BUILD.gn
@@ -74,13 +74,15 @@ static_library("devtools") {
       "//chrome:resources",
       "//chrome:strings",
       "//chrome/app/theme:theme_resources",
-      "//chrome/common/extensions/api",
       "//components/devtools_http_handler",
       "//net:http_server",
       "//skia",
       "//third_party/icu",
       "//third_party/leveldatabase",
     ]
+    if (enable_extensions) {
+      deps += [ "//chrome/common/extensions/api" ]
+    }
     sources += [
       "chrome_devtools_discovery_provider.cc",
       "chrome_devtools_discovery_provider.h",