Implement fetching, caching and retrieval of external policy data

chrome/tools/build/generate_policy_source.py

Index: chrome/tools/build/generate_policy_source.py
diff --git a/chrome/tools/build/generate_policy_source.py b/chrome/tools/build/generate_policy_source.py
index 09c8791abce0fb2d8a53afa1d9a3a6ad66e73454..89987001f5a4281a4016c3473bab997606f3fe5d 100755
--- a/chrome/tools/build/generate_policy_source.py
+++ b/chrome/tools/build/generate_policy_source.py
@@ -25,13 +25,15 @@ class PolicyDetails:
   """Parses a policy template and caches all its details."""
 
   # Maps policy types to a tuple with 3 other types:
-  # - the equivalent base::Value::Type
+  # - the equivalent base::Value::Type or 'TYPE_EXTERNAL' if the policy
+  #   references external data
   # - the equivalent Protobuf field type
   # - the name of one of the protobufs for shared policy types
   # TODO(joaodasilva): refactor the 'dict' type into a more generic 'json' type
   # that can also be used to represent lists of other JSON objects.
   TYPE_MAP = {
     'dict':         ('TYPE_DICTIONARY',   'string',       'String'),
+    'external':     ('TYPE_EXTERNAL',     'string',       'String'),
     'int':          ('TYPE_INTEGER',      'int64',        'Integer'),
     'int-enum':     ('TYPE_INTEGER',      'int64',        'Integer'),
     'list':         ('TYPE_LIST',         'StringList',   'StringList'),
@@ -70,13 +72,14 @@ class PolicyDetails:
     if not PolicyDetails.TYPE_MAP.has_key(policy['type']):
       raise NotImplementedError('Unknown policy type for %s: %s' %
                                 (policy['name'], policy['type']))
-    self.value_type, self.protobuf_type, self.policy_protobuf_type = \
+    self.policy_type, self.protobuf_type, self.policy_protobuf_type = \
         PolicyDetails.TYPE_MAP[policy['type']]
 
     self.desc = '\n'.join(
         map(str.strip,
             PolicyDetails._RemovePlaceholders(policy['desc']).splitlines()))
     self.caption = PolicyDetails._RemovePlaceholders(policy['caption'])
+    self.max_size = policy.get('max_size', 0)
 
     items = policy.get('items')
     if items is None:
@@ -202,6 +205,7 @@ def _WritePolicyConstantHeader(policies, os, f):
           '\n'
           '#include <string>\n'
           '\n'
+          '#include "base/basictypes.h"\n'
           '#include "base/values.h"\n'
           '\n'
           'namespace policy {\n\n')
@@ -211,14 +215,16 @@ def _WritePolicyConstantHeader(policies, os, f):
             'configuration resides.\n'
             'extern const wchar_t kRegistryChromePolicyKey[];\n')
 
-  f.write('// Lists policy types mapped to their names and expected types.\n'
-          '// Used to initialize ConfigurationPolicyProviders.\n'
+  f.write('// Lists metadata such as name, expected type and id for all\n'
+          '// policies. Used to initialize ConfigurationPolicyProviders and\n'
+          '// CloudExternalDataManagers.\n'
           'struct PolicyDefinitionList {\n'
           '  struct Entry {\n'
           '    const char* name;\n'
           '    base::Value::Type value_type;\n'
           '    bool device_policy;\n'
           '    int id;\n'
+          '    size_t max_external_data_size;\n'
           '  };\n'
           '\n'
           '  const Entry* begin;\n'
@@ -245,6 +251,10 @@ def _WritePolicyConstantHeader(policies, os, f):
 
 #------------------ policy constants source ------------------------#
 
+def _GetValueType(policy_type):
+  return policy_type if policy_type != 'TYPE_EXTERNAL' else 'TYPE_DICTIONARY'
+
+
 def _WritePolicyConstantSource(policies, os, f):
   f.write('#include "base/basictypes.h"\n'
           '#include "base/logging.h"\n'
@@ -257,9 +267,10 @@ def _WritePolicyConstantSource(policies, os, f):
   f.write('const PolicyDefinitionList::Entry kEntries[] = {\n')
   for policy in policies:
     if policy.is_supported:
-      f.write('  { key::k%s, base::Value::%s, %s, %s },\n' %
-          (policy.name, policy.value_type,
-              'true' if policy.is_device_only else 'false', policy.id))
+      f.write('  { key::k%s, base::Value::%s, %s, %s, %s },\n' %
+          (policy.name, _GetValueType(policy.policy_type),
+              'true' if policy.is_device_only else 'false', policy.id,
+              policy.max_size))
   f.write('};\n\n')
 
   f.write('const PolicyDefinitionList kChromePolicyList = {\n'
@@ -434,7 +445,9 @@ CPP_HEAD = '''
 #include "base/json/json_reader.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "base/values.h"
+#include "chrome/browser/policy/cloud/cloud_external_data_manager.h"
 #include "chrome/browser/policy/external_data_fetcher.h"
 #include "chrome/browser/policy/policy_map.h"
 #include "policy/policy_constants.h"
@@ -479,7 +492,9 @@ base::Value* DecodeJson(const std::string& json) {
   return root.release();
 }
 
-void DecodePolicy(const em::CloudPolicySettings& policy, PolicyMap* map) {
+void DecodePolicy(const em::CloudPolicySettings& policy,
+                  base::WeakPtr<CloudExternalDataManager> external_data_manager,
+                  PolicyMap* map) {
 '''
 
 
@@ -498,12 +513,18 @@ def _CreateValue(type, arg):
     return 'base::Value::CreateStringValue(%s)' % arg
   elif type == 'TYPE_LIST':
     return 'DecodeStringList(%s)' % arg
-  elif type == 'TYPE_DICTIONARY':
+  elif type == 'TYPE_DICTIONARY' or type == 'TYPE_EXTERNAL':
     return 'DecodeJson(%s)' % arg
   else:
     raise NotImplementedError('Unknown type %s' % type)
 
 
+def _CreateExternalDataFetcher(type, name):
+  if type == 'TYPE_EXTERNAL':
+    return 'new ExternalDataFetcher(external_data_manager, key::k%s)' % name
+  return 'NULL'
+
+
 def _WritePolicyCode(f, policy):
   membername = policy.name.lower()
   proto_type = '%sPolicyProto' % policy.policy_protobuf_type
@@ -530,10 +551,12 @@ def _WritePolicyCode(f, policy):
           '      }\n'
           '      if (do_set) {\n')
   f.write('        base::Value* value = %s;\n' %
-          (_CreateValue(policy.value_type, 'policy_proto.value()')))
+          (_CreateValue(policy.policy_type, 'policy_proto.value()')))
+  f.write('        ExternalDataFetcher* external_data_fetcher = %s;\n' %
+          _CreateExternalDataFetcher(policy.policy_type, policy.name))
   f.write('        map->Set(key::k%s, level, POLICY_SCOPE_USER,\n' %
           policy.name)
-  f.write('                 value, NULL);\n')
+  f.write('                 value, external_data_fetcher);\n')
   f.write('      }\n'
           '    }\n'
           '  }\n')