Revert "autotest: Send metrics about the various host class' usage."

This reverts commit c2c6d54951e7581b047df233b9f4edfba7ced630.

Reason for revert: Said host classes deleted.

Original change's description:
> autotest: Send metrics about the various host class' usage.
>
> We have a lot of Host classes that we suspect are dead. Start spewing
> some metrics about what classes are actually in use so we can
> confidently start pouring gasoline over them all.
>
> BUG=chromium:834335
> TEST=moblab-generic-vm-pre-cq
>
> Change-Id: I8444906ee7c9cdf99f40da87b2c5658752065611
> Reviewed-on: https://chromium-review.googlesource.com/1022734
> Commit-Ready: ChromeOS CL Exonerator Bot <[email protected]>
> Tested-by: Prathmesh Prabhu <[email protected]>
> Reviewed-by: Prathmesh Prabhu <[email protected]>

Bug: chromium:834335
Change-Id: I2ddb6f649e4eab054ec551f501587648e4e4611d
Reviewed-on: https://chromium-review.googlesource.com/1237089
Commit-Ready: Prathmesh Prabhu <[email protected]>
Tested-by: Prathmesh Prabhu <[email protected]>
Reviewed-by: Aviv Keshet <[email protected]>
diff --git a/server/hosts/base_classes.py b/server/hosts/base_classes.py
index 8d679f8..79d2dfa 100644
--- a/server/hosts/base_classes.py
+++ b/server/hosts/base_classes.py
@@ -17,13 +17,8 @@
 [email protected] (Ryan Stutsman)
 """
 
-from autotest_lib.client.bin import utils
 from autotest_lib.client.common_lib import hosts
-from autotest_lib.server import utils as server_utils
-try:
-    from chromite.lib import metrics
-except ImportError:
-    metrics = utils.metrics_mock
+from autotest_lib.server import utils
 
 
 class Host(hosts.Host):
@@ -67,7 +62,7 @@
     def _initialize(self, *args, **dargs):
         super(Host, self)._initialize(*args, **dargs)
 
-        self.serverdir = server_utils.get_server_dir()
+        self.serverdir = utils.get_server_dir()
         self.env = {}
 
 
@@ -77,41 +72,3 @@
 
         if self.job:
             self.job.hosts.discard(self)
-
-
-_CREATION_METRIC_WHITELIST = {
-        'AbstractSSHHost',
-        'ADBHost',
-        'CastOSHost',
-        'ChameleonHost',
-        'CrosHost',
-        'EmulatedAdbHost',
-        'GceHost',
-        'JetstreamHost',
-        'MoblabHost',
-        'PlanktonHost',
-        'ServoHost',
-        'SonicHost',
-        'SSHHost',
-        'TestBed',
-        'TestStationHost',
-}
-_CREATION_METRIC = '/chrome/infra/chromeos/autotest/host/class_instantiated'
-
-
-def send_creation_metric(host, context=''):
-    """Send a metric about which host class we ended up creating.
-
-    Creating host classes is black magic. Once a host class has been created
-    through the various channels, use this function to report what got created.
-
-    @param host: An instace of one of the host classes to send a report about.
-    @param context: Optional context for who created the host instance.
-    """
-    bases = {b.__name__ for b in host.__class__.__bases__}
-    bases = bases & _CREATION_METRIC_WHITELIST
-    for base in bases:
-        metrics.Counter(_CREATION_METRIC).increment(fields={
-                'class': base,
-                'context': context,
-        })