Update Chromium code review docs to reflect 2P review policy

R=jsca@google.com

Change-Id: Ic9b52969fb28cd87c6b0ae0fd2899a8977a5890e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4954782
Reviewed-by: Joey Scarr <jsca@google.com>
Commit-Queue: Ramzi Nasnas <rnasnas@google.com>
Cr-Commit-Position: refs/heads/main@{#1218573}

docs/code_reviews.md

@@ -10,15 +10,19 @@ and OWNERS policy changes launched on March 24, 2021, see
 
 # Code review policies
 
-Ideally the reviewer is someone who is familiar with the area of code you are
-touching. Any committer can review code, but an owner must provide a review
-for each directory you are touching. If you have doubts, look at the `git blame`
-for the file and the `OWNERS` files ([more info](#owners-files)).
+Any [committer](https://www.chromium.org/getting-involved/become-a-committer/#what-is-a-committer) can review code, but
+an owner must provide a review for each directory you are touching. Ideally you should choose
+reviewers who are familiar with the area of code you are touching. If you have doubts, look
+at the `git blame` for the file and the `OWNERS` files ([more info](#owners-files)).
 
 To indicate a positive review, the reviewer provides a `Code-Review +1` in
 Gerrit, also known as an LGTM ("Looks Good To Me"). A score of "-1" indicates
 the change should not be submitted as-is.
 
+Submissions to the chromium/src repository by a change contributor who is not a Chromium
+committer require two committers to Code-Review+1 the submission. If the owner of the CL
+is already a committer, then only one other committer is needed to review.
+
 If you have multiple reviewers, provide a message indicating what you expect
 from each reviewer. Otherwise people might assume their input is not required
 or waste time with redundant reviews.

docs/contributing.md

@@ -233,15 +233,20 @@ policies][code-reviews] page.
 
 ### Finding a reviewer
 
-Ideally, the reviewer is someone who is familiar with the area of code in
-question. If you're not sure who that should be, check with anyone in the
-nearest ancestor OWNERS file.
+Please note here that a "reviewer" in this context is someone that not
+only provides comment on the CL but also someone who can approve the
+submission by providing a CR+1.
 
-- Anybody can review code, but there must be at least one owner for each
-  affected directory.
-- If there are multiple reviewers, make it clear what each reviewer is expected
-  to review.
-- `git cl owners` automatically suggests reviewers based on the OWNERS files.
+Reviewers must be [committers](https://www.chromium.org/getting-involved/become-a-committer/).
+Ideally they should be committers who are familiar with the area of code
+in question. If you're not sure who these should be, check with anyone in
+the nearest ancestor OWNERS file.
+
+- There must be at least one owner for each affected directory.
+- If there are multiple reviewers, make it clear what each reviewer is
+expected to review.
+- `git cl owners` automatically suggests reviewers based on the OWNERS
+files.
 
 _Note:_ By default, please only select one reviewer for each file (that is, a
 single reviewer may review multiple files, but typically each file only needs
@@ -257,6 +262,11 @@ desirable - such as when the code is particularly complicated, or when the file
 uses multiple systems and a perspective from each is valuable. In this case,
 please make it explicit that you would like both reviewers to review.
 
+Submissions to the chromium/src repository by a change contributor who is
+not a Chromium committer will require two committers to Code-Review+1 the
+submissions. If the owner of the CL is already a committer, then only one
+other committer is needed to Code-Review+1.
+
 ### Requesting review
 
 Open the change on [the web][crrev]. If you can't find the link, running `git