Update Java checkstyle naming convention for static final fields.

tools/android/checkstyle/chromium-style-5.0.xml

Index: tools/android/checkstyle/chromium-style-5.0.xml
diff --git a/tools/android/checkstyle/chromium-style-5.0.xml b/tools/android/checkstyle/chromium-style-5.0.xml
index 63c869e749bbe5bbdd77b24ca7f300ef7cc81f14..dda0772997e2193ac7690f011ada6ebce5254f96 100644
--- a/tools/android/checkstyle/chromium-style-5.0.xml
+++ b/tools/android/checkstyle/chromium-style-5.0.xml
@@ -46,7 +46,8 @@
     </module>
     <module name="ConstantName">
       <property name="severity" value="warning"/>
-      <message key="name.invalidPattern" value="Variable ''{0}'' is a constant and thus should be in ALL_CAPS."/>
+      <property name="format" value="^([A-Z][A-Z0-9]*(_[A-Z0-9]+)*)|(s[A-Z][a-zA-Z0-9]*)$"/>
+      <message key="name.invalidPattern" value="Static final field names must either be all caps (e.g. int HEIGHT_PX) for 'true' constants, or start with s (e.g. AtomicInteger sNextId or Runnable sSuspendTask) for fields with mutable state or that don't 'feel' like constants."/>
     </module>
     <!-- Non-public, non-static field names start with m. -->
     <module name="MemberName">