Define Print Preview default printer selection policy

components/policy/resources/policy_templates.json

 {
 # policy_templates.json - Metafile for policy templates
 #
 # The content of this file is evaluated as a Python expression.
 #
 # This file is used as input to generate the following policy templates:
 # ADM, ADMX+ADML, MCX/plist and html documentation.
 #
 # Policy templates are user interface definitions or documents about the
 # policies that can be used to configure Chrome. Each policy is a name-value
@@ skipping 105 matching lines @@
 #   templates and documentation. The policy definition list that Chrome sees
 #   will include policies marked with 'future'. If a WIP policy isn't meant to
 #   be seen by the policy providers either, the 'supported_on' key should be set
 #   to an empty list.
 #
 # IDs:
 #   Since a Protocol Buffer definition is generated from this file, unique and
 #   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: 307
+#   For your editing convenience: highest ID currently used: 308
 #
 # Placeholders:
 #   The following placeholder strings are automatically substituted:
 #     $1 -> Google Chrome / Chromium
 #     $2 -> Google Chrome OS / Chromium OS
 #     $3 -> Google Chrome Frame / Chromium Frame
 #     $6 is reserved for doc_writer
 #
 # Device Policy:
 #   An additional flag 'device_only' (optional, defaults to False) indicates
@@ skipping 3966 matching lines @@
       'example_value': False,
       'id': 117,
       'caption': '''Disable Print Preview (deprecated)''',
       'desc': '''Show the system print dialog instead of print preview.
 
       When this setting is enabled, <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> will open the system print dialog instead of the built-in print preview when a user requests a page to be printed.
 
       If this policy is not set or is set to false, print commands trigger the print preview screen.''',
     },
     {
+      'name': 'PrintPreviewDefaultPrinterSelection',
+      'type': 'string',
+      'schema': { 'type': 'string' },
+      'supported_on': ['chrome.*:48-', 'chrome_os:48-'],
+      'features': {
+        'dynamic_refresh': True,
+        'per_profile': True,
+      },
+      'example_value': '{ "kind": "cloud", "idPattern": ".*public", "namePattern": ".*Color" }',
+      'id': 308,
+      'caption': '''Default printer selection rules''',
+      'desc': '''Overrides <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> default printer selection rules.
+
+      This policy determines the rules for selecting the default printer in <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> which happens the first time the print function is used with a profile.
+
+      When this policy is set, <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> will attempt to find a printer matching the specified attributes, printer type, printer id and name pattern, and select it as default printer.

[Thiemo Nagel, 2015/10/12 19:10:09]

I think this would be clearer if the attributes weren't listed again, eg.:

"matching the specified attributes, printer type, printer id and name pattern,"
--> "matching all of the specified attributes"

BTW: What happens if the match is non-unique?  Which printer will be selected in
that case?  And what if there is no match?

[Aleksey Shlyapnikov, 2015/10/13 18:14:57]

Thank you for pointing that out, mentioned these cases too. Done.

+
+      If this policy is not set, the printer defaults to built-in PDF printer or no printer selected, when PDF printer is not available.
+
+      The value is parsed as JSON object, conforming to the following schema:
+      {
+        "type": "object",
+        "properties": {
+          "kind": {
+            "description": "Whether to limit the search of the matching printer to a specific set of printers.",
+            "type": {
+              "enum": [ "local", "cloud" ]
+            }
+          },
+          "idPattern": {
+            "description": "Regular expression to match printer id.",
+            "type": "string"
+          },
+          "namePattern": {
+            "description": "Regular expression to match printer display name.",
+            "type": "string"
+          }
+        }
+      }
+
+      Printers connected to Google Cloud Print are considered "cloud", the rest of the printers are classified as "local".
+      Omitting a field means all values match, for example, not specifying connectivity will cause Print Preview to initiate the discovery of all kinds of printers, local and cloud.
+      Regular expression patterns are case sensistive.''',
+    },
+    {
       'name': 'DisableSSLRecordSplitting',
       'type': 'main',
       'schema': { 'type': 'boolean' },
       'supported_on': ['chrome.*:18-', 'chrome_os:18-'],
       'features': {
         'dynamic_refresh': True,
         'per_profile': False,
       },
       'example_value': True,
       'id': 118,
@@ skipping 3518 matching lines @@
       'desc': '''Text appended in parentheses next to the policies top-level container to indicate that those policies are of the Recommended level''',
       'text': 'Default Settings (users can override)',
     },
     'doc_complex_policies_on_windows': {
       'desc': '''Text pointing the user to a help article for complex policies on Windows''',
       'text': '''encoded as a JSON string, for details see <ph name="COMPLEX_POLICIES_URL">https://www.chromium.org/administrators/complex-policies-on-windows<ex>https://www.chromium.org/administrators/complex-policies-on-windows</ex></ph>''',
     },
   },
   'placeholders': [],
 }