Soften some language in styleguide/c++/checks.md

A paragraph saying that we reserve the right to upgrade DCHECKs to
CHECKs is removed as it suggests that changes will be made to DCHECKs
under the hood bypassing code reviewers. This may have been discouraging
the addition of DCHECKs in the first place.

The intent here is to suggest CHECKs over DCHECKs, it should never be
interpreted as discouraging the addition of CHECKs in the first place.

Bug: None
Change-Id: Ic81114de969e6a9c33c0f4e43a01d3aa49a1f3b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4363704
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Commit-Queue: Peter Boström <pbos@chromium.org>
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1120887}

styleguide/c++/checks.md

@@ -15,9 +15,9 @@ being violated. All invariant failures should be seen as P1 bugs, regardless of
 their crash rate. Continuing past an invariant failure can cause crashes and
 incorrect behaviour for our users, but also frequently presents security
 vulnerabilities as attackers may leverage the unexpected state to take control
-of the program. We also reserve the right to let the compiler assume and
-optimize around `DCHECK()`s holding true in non-DCHECK builds using
-`__builtin_assume()`, which even further formalizes undefined behavior.
+of the program. In the future we may let the compiler assume and optimize around
+`DCHECK()`s holding true in non-DCHECK builds using `__builtin_assume()`, which
+further formalizes undefined behavior.
 
 Prefer `CHECK()` and `NOTREACHED_NORETURN()` as they ensure that if an invariant
 fails, the program does not continue in an unexpected state, and we hear about
@@ -47,9 +47,6 @@ that these are in fact commonly reached. Prefer `NOTREACHED_NORETURN()` in new
 code, while we migrate the preexisting cases to it with care. See
 https://crbug.com/851128.
 
-We reserve the right to make any `DCHECK()` or `NOTREACHED()` statements fatal
-in production builds, subject to performance and code-size constraints.
-
 Below are some examples to explore the choice of `CHECK()` and its variants:
 
 ```c++