Add windows_host_engine_test. (#161992)

Towards https://github.com/flutter/flutter/issues/161990.

engine/src/flutter/.ci.yaml

@@ -554,6 +554,18 @@ targets:
     drone_dimensions:
       - os=Windows
 
+  - name: Windows windows_host_engine_test
+    recipe: engine_v2/engine_v2
+    # TODO(matanlurey): Enable (https://github.com/flutter/flutter/issues/161990).
+    bringup: true
+    timeout: 120
+    properties:
+      config_name: windows_host_engine_test
+    # Do not remove(https://github.com/flutter/flutter/issues/144644)
+    # Scheduler will fail to get the platform
+    drone_dimensions:
+      - os=Windows
+
   - name: Windows windows_arm_host_engine
     recipe: engine_v2/engine_v2
     timeout: 120

engine/src/flutter/ci/builders/windows_host_engine.json

@@ -1,4 +1,12 @@
 {
+    "_comment": [
+        "The builds defined in this file should not contain tests, ",
+        "and the file should not contain builds that are essentially tests. ",
+        "The only builds in this file should be the builds necessary to produce ",
+        "release artifacts. ",
+        "Tests to run on windows hosts should go in one of the other windows_ build ",
+        "definition files."
+    ],
     "builds": [
         {
             "archives": [

engine/src/flutter/ci/builders/windows_host_engine_test.json

@@ -0,0 +1,49 @@
+{
+    "_comment": [
+        "The builds defined in this file should only contain tests, ",
+        "and the file should not contain builds that produce artifacts. "
+    ],
+    "builds": [
+        {
+            "drone_dimensions": [
+                "device_type=none",
+                "os=Windows-10"
+            ],
+            "gclient_variables": {
+                "download_android_deps": false,
+                "download_jdk": false,
+                "use_rbe": true
+            },
+            "gn": [
+                "--target-dir",
+                "ci/host_debug",
+                "--runtime-mode",
+                "debug",
+                "--no-lto",
+                "--no-goma",
+                "--rbe"
+            ],
+            "name": "ci\\host_debug",
+            "description": "Builds host-side unit tests for Windows.",
+            "ninja": {
+                "config": "ci/host_debug",
+                "targets": [
+                    "flutter:unittests"
+                ]
+            },
+            "tests": [
+                {
+                    "language": "python3",
+                    "name": "Host Tests for host_debug",
+                    "script": "flutter/testing/run_tests.py",
+                    "parameters": [
+                        "--variant",
+                        "ci/host_debug",
+                        "--type",
+                        "engine"
+                    ]
+                }
+            ]
+        }
+    ]
+}