Compile core/exported/ with -Wshadow.

Bug: 294205
Change-Id: I579500a705436e6c36b8b56c241ab5f8b5e9018e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2462260Reviewed-by: Nate Chapin <japhet@chromium.org>
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815642}

third_party/blink/renderer/core/exported/BUILD.gn

@@ -5,6 +5,8 @@ import("//build/config/dcheck_always_on.gni")
 import("//third_party/blink/renderer/core/core.gni")
 
 blink_core_sources("exported") {
+  configs += [ "//build/config/compiler:noshadowing" ]
+
   sources = [
     "local_frame_client_impl.cc",
     "local_frame_client_impl.h",

third_party/blink/renderer/core/exported/local_frame_client_impl.cc

@@ -598,9 +598,9 @@ void LocalFrameClientImpl::BeginNavigation(
   } else {
     navigation_info->initiator_frame = nullptr;
   }
-  for (auto& policy : initiator_csp) {
+  for (auto& csp_policy : initiator_csp) {
     navigation_info->initiator_csp.emplace_back(
-        ConvertToPublic(std::move(policy)));
+        ConvertToPublic(std::move(csp_policy)));
   }
   if (initiator_self_source) {
     navigation_info->initiator_self_source =