Do IWYU for base/strings/string_number_conversions.h in //content

Files that use base::NumberToString() and friends should include
string_number_conversions.h directly instead of depending on transitive
includes from far away.

Change-Id: I96ef6103d33014b850d973e187f98414c956462a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6580133
Reviewed-by: Avi Drissman <[email protected]>
Commit-Queue: Avi Drissman <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1464910}
diff --git a/content/browser/renderer_host/navigation_request_unittest.cc b/content/browser/renderer_host/navigation_request_unittest.cc
index 3ee00512..e605f7f 100644
--- a/content/browser/renderer_host/navigation_request_unittest.cc
+++ b/content/browser/renderer_host/navigation_request_unittest.cc
@@ -11,6 +11,7 @@
 #include "base/containers/flat_map.h"
 #include "base/functional/bind.h"
 #include "base/i18n/number_formatting.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/test/scoped_feature_list.h"
 #include "build/build_config.h"
 #include "content/public/browser/navigation_throttle.h"