[Extensions] Fix //extensions deps in //chrome/browser/favicon

Chrome code should rely on extensions targets only if extensions are
enabled (gn arg enable_extensions = true). Fix dependencies in
//chrome/browser/favicon to update the C++ and gn to put
extensions-related logic behind enable-extensions checks and update
dependencies accordingly.

Bug: 731689
Change-Id: Ie38ecbd1f360e2c55bd3992c1291e307676ba945
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3402442
Auto-Submit: Devlin Cronin <[email protected]>
Reviewed-by: Mikel Astiz <[email protected]>
Commit-Queue: Devlin Cronin <[email protected]>
Cr-Commit-Position: refs/heads/main@{#961719}

chrome/browser/favicon/chrome_favicon_client.cc

@@ -11,9 +11,13 @@
 #include "components/bookmarks/browser/bookmark_model.h"
 #include "components/dom_distiller/core/url_constants.h"
 #include "components/dom_distiller/core/url_utils.h"
-#include "extensions/common/constants.h"
+#include "extensions/buildflags/buildflags.h"
 #include "url/gurl.h"
 
+#if BUILDFLAG(ENABLE_EXTENSIONS)
+#include "extensions/common/constants.h"
+#endif
+
 namespace {
 
 void RunFaviconCallbackIfNotCanceled(
@@ -33,8 +37,12 @@ ChromeFaviconClient::~ChromeFaviconClient() {
 }
 
 bool ChromeFaviconClient::IsNativeApplicationURL(const GURL& url) {
-  return url.SchemeIs(content::kChromeUIScheme) ||
-         url.SchemeIs(extensions::kExtensionScheme);
+#if BUILDFLAG(ENABLE_EXTENSIONS)
+  if (url.SchemeIs(extensions::kExtensionScheme))
+    return true;
+#endif
+
+  return url.SchemeIs(content::kChromeUIScheme);
 }
 
 bool ChromeFaviconClient::IsReaderModeURL(const GURL& url) {