Add Value FromDict to Telemetry

tools/telemetry/telemetry/value/scalar.py

Index: tools/telemetry/telemetry/value/scalar.py
diff --git a/tools/telemetry/telemetry/value/scalar.py b/tools/telemetry/telemetry/value/scalar.py
index dbb3a410496f48bbc19af592e7cd622109bddb51..12c11c77fc02bdcbaab905c391120db5e3766d7e 100644
--- a/tools/telemetry/telemetry/value/scalar.py
+++ b/tools/telemetry/telemetry/value/scalar.py
@@ -49,8 +49,8 @@ class ScalarValue(value_module.Value):
   def GetRepresentativeString(self):
     return str(self.value)
 
-  @classmethod
-  def GetJSONTypeName(cls):
+  @staticmethod
+  def GetJSONTypeName():
     return 'scalar'
 
   def AsDict(self):
@@ -58,6 +58,13 @@ class ScalarValue(value_module.Value):
     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 ScalarValue(**kwargs)
+
   @classmethod
   def MergeLikeValuesFromSamePage(cls, values):
     assert len(values) > 0