Update guidelines for OWNERS.

As per the recent discussion on chromium-dev in
https://groups.google.com/a/chromium.org/d/topic/chromium-dev/_e7fn9jJOcI/discussion
this CL updates the text explaining what we expect owners to do,
in particular to clarify that we can make exceptions to the
rules if the owners agree to do so.

R=hiroh@chromium.org

Change-Id: I7d2fb0049ff6ef386417259e49b4091efe4a1e20
Reviewed-on: https://chromium-review.googlesource.com/c/1285969Reviewed-by: Hirokazu Honda <hiroh@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600259}

docs/code_reviews.md

@@ -72,31 +72,34 @@ committer is sufficient.
 
 The existing owners of a directory approve additions to the list. It is
 preferable to have many directories, each with a smaller number of specific
-owners rather than large directories with many owners. Owners must:
+owners rather than large directories with many owners. Owners should:
 
   * Demonstrate excellent judgment, teamwork and ability to uphold Chrome
     development principles.
 
   * Be already acting as an owner, providing high-quality reviews and design
-    feedback
+    feedback.
 
-  * Be a Chromium project member with full commit access of at least 6
+  * Be a Chromium project member with full commit access of at least three
     months tenure.
 
   * Have submitted a substantial number of non-trivial changes to the affected
     directory.
 
   * Have committed or reviewed substantial work to the affected directory
-    within the last 90 days.
+    within the last ninety days.
 
   * Have the bandwidth to contribute to reviews in a timely manner. If the load
     is unsustainable, work to expand the number of owners. Don't try to
     discourage people from sending reviews, including writing "slow" or
     "emeritus" after your name.
 
-Seldom-updated directories may have exceptions to the "substantiality" and
-"recency" requirements. Directories in `third_party` should list those most
-familiar with the library, regardless of how often the code is updated.
+The above are guidelines more than they are hard rules, and exceptions are
+okay as long as there is a consensus by the existing owners for them.
+For example, seldom-updated directories may have exceptions to the
+"substantiality" and "recency" requirements. Directories in `third_party`
+should list those most familiar with the library, regardless of how often
+the code is updated.
 
 ### OWNERS file details