Add a policy to always show the Cast toolbar icon

components/policy/resources/policy_templates.json

Index: components/policy/resources/policy_templates.json
diff --git a/components/policy/resources/policy_templates.json b/components/policy/resources/policy_templates.json
index 5a601818d7b5c991f15f583aecb30ddfec41af0b..e8ccda8beb8a51e2fb6c69e94285f5b46c12edf8 100644
--- a/components/policy/resources/policy_templates.json
+++ b/components/policy/resources/policy_templates.json
@@ -139,7 +139,7 @@
 #   persistent IDs for all fields (but not for groups!) are needed. These are
 #   specified by the 'id' keys of each policy. NEVER CHANGE EXISTING IDs,
 #   because doing so would break the deployed wire format!
-#   For your editing convenience: highest ID currently used: 356
+#   For your editing convenience: highest ID currently used: 357
 #
 # Placeholders:
 #   The following placeholder strings are automatically substituted:
@@ -9339,6 +9339,23 @@
         },
       ],
     },
+    {
+      'name': 'ShowCastIconInToolbar',
+      'type': 'main',
+      'schema': { 'type': 'boolean' },
+      'supported_on': ['chrome.*:57-', 'chrome_os:57-'],
+      'features': {
+        'dynamic_refresh': False,
+        'per_profile': True,
+      },
+      'example_value': False,
+      'id': 357,
+      'caption': '''Shows the Cast toolbar icon''',
+      'tags': [],
+      'desc': '''If this policy is set to true, the Cast toolbar icon will always be shown on the toolbar or the overflow menu, and users will not be able to remove it.
+
+      If this policy is set to false or not set, users will be able to pin or remove the icon via its contextual menu.'''
+    },
   ],
   'messages': {
     # Messages that are not associated to any policies.