refactor: fix modernize-return-braced-init-list warnings (#44857)

* refactor: avoid repeating the return type from the declaration; use a braced initializer list instead [modernize-return-braced-init-list]

Co-authored-by: Charles Kerr <charles@charleskerr.com>

* refactor: avoid repeating the return type from the declaration; use a braced initializer list instead [modernize-return-braced-init-list]

NB: using the braced-initializer list uncovered an error here:
the float returned by std::floor() can't be implicitly cast to
an int. This is solved by using base::ClampFloor<int>() instead.
std::floor()

Co-authored-by: Charles Kerr <charles@charleskerr.com>

---------

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Charles Kerr <charles@charleskerr.com>

shell/browser/api/electron_api_view.cc

@@ -282,7 +282,7 @@ void View::SetBounds(const gfx::Rect& bounds) {
 
 gfx::Rect View::GetBounds() {
   if (!view_)
-    return gfx::Rect();
+    return {};
   return view_->bounds();
 }