Add Value FromDict to Telemetry

tools/telemetry/telemetry/value/string.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from telemetry import value as value_module
 from telemetry.value import list_of_string_values
 
 class StringValue(value_module.Value):
   def __init__(self, page, name, units, value, important=True,
                description=None):
@@ skipping 29 matching lines @@
     # Buildbot's print_perf_results method likes to get lists for all values,
     # even when they are scalar, so list-ize the return value.
     return [self.value]
 
   def GetRepresentativeNumber(self):
     return self.value
 
   def GetRepresentativeString(self):
     return str(self.value)
 
-  @classmethod
-  def GetJSONTypeName(cls):
+  @staticmethod
+  def GetJSONTypeName():
     return 'string'
 
   def AsDict(self):
     d = super(StringValue, self).AsDict()
     d['value'] = self.value
     return d
 
+  @staticmethod
+  def FromDict(value_dict, page_dict):
+    kwargs = value_module.Value.GetConstructorKwArgs(value_dict, page_dict)
+    kwargs['value'] = value_dict['value']
+
+    return StringValue(**kwargs)
+
   @classmethod
   def MergeLikeValuesFromSamePage(cls, values):
     assert len(values) > 0
     v0 = values[0]
     return list_of_string_values.ListOfStringValues(
         v0.page, v0.name, v0.units,
         [v.value for v in values],
         important=v0.important)
 
   @classmethod
   def MergeLikeValuesFromDifferentPages(cls, values,
                                         group_by_name_suffix=False):
     assert len(values) > 0
     v0 = values[0]
     if not group_by_name_suffix:
       name = v0.name
     else:
       name = v0.name_suffix
     return list_of_string_values.ListOfStringValues(
         None, name, v0.units,
         [v.value for v in values],
         important=v0.important)