Adding a DownloadRestrictions group 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 121 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: 362
+#   For your editing convenience: highest ID currently used: 363
 #   And don't forget to also update the EnterprisePolicies enum of
 #   histograms.xml.
 #
 # 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
 #
@@ skipping 136 matching lines @@
     {
       'name': 'NewTabPage',
       'type': 'group',
       'caption': '''New Tab Page''',
       'desc': '''Configure the default New Tab page in <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph>.''',
       'policies': [
         {
           'name': 'NewTabPageLocation',
           'type': 'string',
           'schema': { 'type': 'string' },
-          'supported_on': ['chrome.*:57-', 'chrome_os:57-'],
+          'supported_on': ['chrome.*:58-', 'chrome_os:58-'],
           'features': {
             'can_be_recommended': True,
             'dynamic_refresh': True,
             'per_profile': True,
           },
           'example_value': 'https://www.chromium.org',
           'id': 360,
           'caption': '''Configure the New Tab page URL''',
           'tags': [],
           'desc': '''Configures the default New Tab page URL in <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> and prevents users from changing it.
@@ skipping 1372 matching lines @@
       'desc': '''Configures the cache size that <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> will use for storing cached media files on the disk.
 
       If you set this policy, <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> will use the provided cache size regardless whether the user has specified the '--media-cache-size' flag or not. The value specified in this policy is not a hard boundary but rather a suggestion to the caching system, any value below a few megabytes is too small and will be rounded up to a sane minimum.
 
       If the value of this policy is 0, the default cache size will be used but the user will not be able to change it.
 
       If this policy is not set the default size will be used and the user will be able to override it with the --media-cache-size flag.''',
       'label': '''Set media disk cache size''',
     },
     {
+      'name': 'DownloadRestrictions',
+      'type': 'int-enum',
+      'schema': {
+        'type': 'integer',
+        'enum': [ 0, 1, 2, 3 ],
+      },
+      'items': [
+        {
+          'name': 'AllowDownloads',
+          'value': 0,
+          'caption': '''No restrictions''',
+        },
+        {
+          'name': 'DisableBlockedFiles',
+          'value': 1,
+          'caption': '''All downloads allowed, except for those that carry SafeBrowsing warnings.''',

[pastarmovj, 2017/02/06 07:45:00]

I know this CL is only a prototype still but I will put some comments here that
are more nits than actual issues.

The caption is too long and won't show well in the policy editor on windows. I
would go with a short cation e.g. "Allow all downloads" and then have a
paragraph about what each option does explained in the description below.

[MAD, 2017/02/06 19:41:33]

Done.

+        },
+        {
+          'name': 'DisableBlockedAndDangerousFiles',
+          'value': 2,
+          'caption': '''All downloads allowed, except for those that carry SafeBrowsing warnings or are of potentially dangerous filetypes.''',
+        },
+        {
+          'name': 'DisableDownloads',
+          'value': 3,
+          'caption': '''No downloads allowed, download functionality is disabled.''',
+        },
+      ],
+      'supported_on': ['chrome.*:58-', 'chrome_os:58-'],
+      'features': {
+        'can_be_recommended': True,
+        'dynamic_refresh': True,
+        'per_profile': True,
+      },
+      'example_value': 2,
+      'id': 363,
+      'caption': '''Allow download restrictions''',
+      'tags': ['local-data-access'],
+      'desc': '''Configures the type of downloads that <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> will allow.
+
+      If you set this policy, <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> will prevent certain types of downloads.''',
+      'label': '''Allow download restrictions''',

[pastarmovj, 2017/02/06 07:45:00]

Download restrictions" might be a better name imho.

[MAD, 2017/02/06 19:41:33]

Done.

+    },
+    {
       'name': 'DownloadDirectory',
       'type': 'string',
       'schema': { 'type': 'string' },
       'supported_on': ['chrome.*:11-', 'chrome_os:35-'],
       'features': {
         'can_be_recommended': True,
         'dynamic_refresh': True,
         'per_profile': True,
       },
       'example_value': '/home/${user_name}/Downloads',
@@ skipping 7943 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': [],
 }