Add a mechanism to force parameters of a group to a specific value.

components/variations/variations_associated_data.h

Index: components/variations/variations_associated_data.h
diff --git a/components/variations/variations_associated_data.h b/components/variations/variations_associated_data.h
index 79f31a31e0516904de7f7a262a785d8742cdefdd..8e9204e48a9abcce5219ee44cf901aa7b4555ecd 100644
--- a/components/variations/variations_associated_data.h
+++ b/components/variations/variations_associated_data.h
@@ -113,6 +113,14 @@ bool AssociateVariationParams(const std::string& trial_name,
                               const std::string& group_name,
                               const std::map<std::string, std::string>& params);
 
+// Provide a mechanism to associate multiple set of params to multiple groups

[Alexei Svitkine (slow), 2015/04/29 15:34:25]

Nit: Provide -> Provides

[danduong, 2015/04/29 21:00:09]

Done.

+// with a formatted string specified from commandline. For example:
+// "trial1.group1:k1/v1/k2/v2,trial2.group2:k1/v1" defines parameters for two
+// variations. One of which is identified with trial name "trial1" and group
+// name "group1". This variation also has two key/value pairs associated in the
+// paramenters (k1,v1 and k2,v2).

[Alexei Svitkine (slow), 2015/04/29 15:34:25]

Mention something about the escape format.

You could also leave this description brief and reference the comment on the
command-line flag declaration.

[danduong, 2015/04/29 21:00:09]

Done.

+bool AssociateParamsFromString(const std::string& variations_string);
+
 // Retrieves the set of key-value |params| for the variation associated with
 // the specified field trial, based on its selected group. If the field trial
 // does not exist or its selected group does not have any parameters associated