Specify some tests for 64-bit Windows 10.

testing/buildbot/chromium.win.json

Index: testing/buildbot/chromium.win.json
diff --git a/testing/buildbot/chromium.win.json b/testing/buildbot/chromium.win.json
index 61c3ef724cae9ebcf8dca7f65a53c36392296497..081fd63259cc71606d3c62bd1af809b7c6403e09 100644
--- a/testing/buildbot/chromium.win.json
+++ b/testing/buildbot/chromium.win.json
@@ -797,6 +797,34 @@
       }
     ]
   },
+  "Win10 Tests x64": {
+    "gtest_tests": [
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "base_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "sbox_integration_tests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "sbox_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "sbox_validation_tests"
+      }
+    ]
+  },
   "Win7 (32) Tests": {
     "gtest_tests": [
       {