Adding Variable builders to cover all builders under master "chromium"

masters/master.tryserver.chromium.android/builders.pyl

 {
   "master_base_class": "Master4a",
   "master_port": 21401,
   "master_port_alt": 41401,
   "slave_port": 31401,
   "templates": ["templates", "../master.chromium/templates"],
 
   "service_account_file": "service-account-chromium-tryserver.json",
   "buildbucket_bucket": "master.tryserver.chromium.android",
 
@@ skipping 124 matching lines @@
       "scheduler": None,
       "slavebuilddir": "android",
       "slave_pools": ["slaves_with_devices_cq"],
     },
     "android_chromium_variable": {
       "builder_timeout_s": 6900,  # 60 * 115
       "recipe": "findit/chromium/compile",
       "scheduler": None,
       "slavebuilddir": "android_chromium_variable",
       "slave_pools": ["ccompute_bots_cq"],
-    }
+    },
+    "android_chromium_variable_archive": {
+      "builder_timeout_s": 6900,  # 60 * 115
+      "recipe": "findit/chromium/compile",
+      "scheduler": None,
+      "slavebuilddir": "android_chromium_variable_archive",
+      "slave_pools": ["ccompute_bots_cq"],

[Sergey Berezin, 2016/03/16 01:52:20]

The disk space on this pool is very healthy, adding a new build folder is fine:
http://shortn/_qIec7MCxuZ

However, please keep in mind that this pool is already slightly overloaded:
https://goto.google.com/salqx

[stgao, 2016/03/16 07:32:58]

Jeff, we need to be careful about using cq slave pools.
Is it possible to have an optional slave pool like those in win/mac/linux
tryservers that we use?

+    },
   },
 
   "schedulers": { },
 
   "slave_pools": {
     "slaves_with_devices_cq": {
       "slave_data": {
         "os": "linux",
         "version": "precise",
         "bits": 64,
@@ skipping 209 matching lines @@
         "bits": 64,
       },
       "slaves": [
         "build199-a4",
         "build38-b4",
         "build97-b4",
       ],
     },
   }
 }