Rename "base::raw_ptr" into "raw_ptr".

The shorter form is the one to be used.
Pointers in ChromeOS ash used not to be rewritten and it is not enforced
yet. Folks started to use them, and the `base::raw_ptr` pattern emerged.

This is a fully automated patch to fix it. Script:

```
git grep -lz "base::raw_ptr<" | xargs -0 sed -i 's/base::raw_ptr</raw_ptr</g'
git grep -lz "base::raw_ref<" | xargs -0 sed -i 's/base::raw_ref</raw_ref</g'
git checkout HEAD~ base/
git checkout HEAD~ tools/
git cl format
```

Bug: None
Change-Id: I0814bafe9f47b93be0b73d84ee52b058d1ad368f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4476651
Reviewed-by: Bartek Nowierski <bartekn@chromium.org>
Owners-Override: Bartek Nowierski <bartekn@chromium.org>
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1135823}

diff --git a/ash/shelf/login_shelf_widget.cc b/ash/shelf/login_shelf_widget.cc
index e083fcd..bcbd0d37 100644
--- a/ash/shelf/login_shelf_widget.cc
+++ b/ash/shelf/login_shelf_widget.cc

@@ -75,7 +75,7 @@
   }
 
  private:
-  const base::raw_ptr<Shelf> shelf_ = nullptr;
+  const raw_ptr<Shelf> shelf_ = nullptr;
 
   // When true, the default focus of the shelf is the last focusable child.
   bool default_last_focusable_child_ = false;