Windows 10 64-bit try server configuration.

scripts/slave/recipe_modules/chromium_tests/chromium_win.py

Index: scripts/slave/recipe_modules/chromium_tests/chromium_win.py
diff --git a/scripts/slave/recipe_modules/chromium_tests/chromium_win.py b/scripts/slave/recipe_modules/chromium_tests/chromium_win.py
index ceb9f2739449c14be60bdce2fc0e1fcf62fba37d..ecb90a3e5dc2d44ea4900bd883a22630adbf07e5 100644
--- a/scripts/slave/recipe_modules/chromium_tests/chromium_win.py
+++ b/scripts/slave/recipe_modules/chromium_tests/chromium_win.py
@@ -35,6 +35,33 @@ SPEC = {
       'enable_swarming': True,
       'use_isolate': True,
     },
+    'Win10 Tests x64': {
+      'chromium_config': 'chromium',
+      'chromium_apply_config': ['mb', 'ninja_confirm_noop'],
+      'gclient_config': 'chromium',
+      'chromium_config_kwargs': {
+        'BUILD_CONFIG': 'Release',
+        'TARGET_BITS': 64,
+      },
+      'bot_type': 'tester',
+      'test_generators': [
+        steps.generate_gtest,
+        steps.generate_script,
+        steps.generate_isolated_script,
+      ],
+      'tests': [
+        steps.MiniInstallerTest(),
+      ],
+      'parent_buildername': 'Win x64 Builder',
+      'testing': {
+        'platform': 'win',
+      },
+      'enable_swarming': True,
+      'swarming_dimensions': {
+        'cpu': 'x86-64',
+        'os': 'Windows-10-10240',
+      },
+    },
     'Win7 (32) Tests': {
       'chromium_config': 'chromium',
       'chromium_apply_config': ['ninja_confirm_noop'],