Add authorize_adb_keys step that will add host key to device.

scripts/slave/recipes/android/perf.expected/provision_devices.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/bot_update.py",
       "--master",
       "chromium.perf",
       "--builder",
       "Android Nexus5 Perf",
@@ skipping 144 matching lines @@
       "[SLAVE_BUILD]/src/build/android/adb_logcat_monitor.py",
       "[SLAVE_BUILD]/src/out/logcat"
     ],
     "env": {
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },
     "name": "spawn_logcat_monitor"
   },
   {
     "cmd": [
+      "[BUILD]/scripts/slave/android/authorize_adb_devices"
+    ],
+    "env": {
+      "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
+    },
+    "name": "authorize_adb_devices"
+  },
+  {
+    "cmd": [
       "[SLAVE_BUILD]/src/build/android/buildbot/bb_device_status_check.py",
       "--json-output",
       "/path/to/tmp/json"
     ],
     "env": {
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },
     "name": "device_status_check",
     "~followup_annotations": [
       "@@@STEP_TEXT@Online devices: 1@@@",
@@ skipping 43 matching lines @@
       "step returned non-zero exit code: 1",
       "@@@STEP_EXCEPTION@@@"
     ]
   },
   {
     "name": "$final_result",
     "reason": "Infra Failure: Step('provision_devices') returned 1",
     "status_code": 1
   }
 ]