Compile core/fetch/ with -Wshadow.

Bug: 294205
Change-Id: Ief9e9bc948019a6d74ec15781e96dd3917879794
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2462261Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816107}

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

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

third_party/blink/renderer/core/fetch/fetch_data_loader.cc

@@ -169,12 +169,12 @@ class FetchDataLoaderAsArrayBuffer final : public FetchDataLoader,
           NOTREACHED();
           return;
         case BytesConsumer::Result::kDone: {
-          DOMArrayBuffer* result = BuildArrayBuffer();
-          if (!result) {
+          DOMArrayBuffer* array_buffer = BuildArrayBuffer();
+          if (!array_buffer) {
             client_->DidFetchDataLoadFailed();
             return;
           }
-          client_->DidFetchDataLoadedArrayBuffer(result);
+          client_->DidFetchDataLoadedArrayBuffer(array_buffer);
           return;
         }
         case BytesConsumer::Result::kError: