Rename {absl => std}::optional in //content/

Automated patch, intended to be effectively a no-op.

Context:
https://groups.google.com/a/chromium.org/g/cxx/c/nBD_1LaanTc/m/ghh-ZZhWAwAJ?utm_medium=email&utm_source=footer

As of https://crrev.com/1204351, absl::optional is now a type alias for
std::optional. We should migrate toward it.

Script:
```
function replace {
  echo "Replacing $1 by $2"
  git grep -l "$1" \
    | cut -f1 -d: \
    | grep \
      -e "^content" \
    | sort \
    | uniq \
    | grep \
      -e "\.h" \
      -e "\.cc" \
      -e "\.mm" \
      -e "\.py" \
    | xargs sed -i "s/$1/$2/g"
}
replace "absl::make_optional" "std::make_optional"
replace "absl::optional" "std::optional"
replace "absl::nullopt" "std::nullopt"
replace "absl::in_place" "std::in_place"
replace "absl::in_place_t" "std::in_place_t"
replace "\"third_party\/abseil-cpp\/absl\/types\/optional.h\"" "<optional>"
git cl format
```

# Skipping unrelated "check_network_annotation" errors.
NOTRY=True

Bug: chromium:1500249
Change-Id: Icfd31a71d8faf63a2e8d5401127e7ee74cc1c413
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5185537
Auto-Submit: Arthur Sonzogni <[email protected]>
Commit-Queue: Arthur Sonzogni <[email protected]>
Owners-Override: Avi Drissman <[email protected]>
Reviewed-by: Avi Drissman <[email protected]>
Reviewed-by: danakj <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1245739}
diff --git a/content/renderer/pepper/video_encoder_shim.h b/content/renderer/pepper/video_encoder_shim.h
index ead3ab72..e088faa 100644
--- a/content/renderer/pepper/video_encoder_shim.h
+++ b/content/renderer/pepper/video_encoder_shim.h
@@ -51,7 +51,7 @@
   void RequestEncodingParametersChange(
       const media::Bitrate& bitrate,
       uint32_t framerate,
-      const absl::optional<gfx::Size>& size) override;
+      const std::optional<gfx::Size>& size) override;
   void Destroy() override;
 
  private: