[Android] Use more specific host platforms for devil.

BUG=566160,566170

Review URL: https://codereview.chromium.org/1501843002

Cr-Commit-Position: refs/heads/master@{#363488}
diff --git a/build/android/test_runner.py b/build/android/test_runner.py
index 9f1b22e..9a74f03c 100755
--- a/build/android/test_runner.py
+++ b/build/android/test_runner.py
@@ -19,6 +19,7 @@
 import devil_chromium
 
 from devil import base_error
+from devil import devil_env
 from devil.android import apk_helper
 from devil.android import device_blacklist
 from devil.android import device_errors
@@ -122,7 +123,7 @@
   if args.adb_path:
     devil_custom_deps = {
       'adb': {
-        'android_host': [args.adb_path]
+        devil_env.GetPlatform(): [args.adb_path]
       }
     }