Allow component installers to specify a map of installer attributes.

components/update_client/update_client.h

Index: components/update_client/update_client.h
diff --git a/components/update_client/update_client.h b/components/update_client/update_client.h
index 0c0e42d20c8d62e838e7990ba37678befd1446be..5f1a8ebb7308ce92322b87d334911229cb93efda 100644
--- a/components/update_client/update_client.h
+++ b/components/update_client/update_client.h
@@ -7,6 +7,7 @@
 
 #include <stdint.h>
 
+#include <map>
 #include <memory>
 #include <string>
 #include <vector>
@@ -182,6 +183,10 @@ class CrxInstaller : public base::RefCountedThreadSafe<CrxInstaller> {
   virtual ~CrxInstaller() {}
 };
 
+// A dictionary of installer-specific, arbitrary name-value pairs, which
+// may be used in the update checks requests.
+using InstallerAttributes = std::map<std::string, std::string>;
+
 // TODO(sorin): this structure will be refactored soon.
 struct CrxComponent {
   CrxComponent();
@@ -198,7 +203,12 @@ struct CrxComponent {
 
   std::string fingerprint;  // Optional.
   std::string name;         // Optional.
-  std::string ap;           // Optional. Must match ^[-+_=a-zA-Z0-9]{0,256}$
+
+  // Optional.
+  // Valid values for the name part of an attribute match
+  // ^[-_a-zA-Z0-9]{1,256}$ and valid values the value part of an attribute
+  // match ^[-.,;+_=a-zA-Z0-9]{0,256}$ .
+  InstallerAttributes installer_attributes;
 
   // Specifies that the CRX can be background-downloaded in some cases.
   // The default for this value is |true|.