Add a hardware_class attribute (for HWID, HWQual ID) to the Omaha request.

BUG=1600
TEST=unit tests, gmerge and looked at request logs

Review URL: http://codereview.chromium.org/3007020
diff --git a/action_pipe.h b/action_pipe.h
index 7697043..4681627 100644
--- a/action_pipe.h
+++ b/action_pipe.h
@@ -41,9 +41,7 @@
 template<typename ObjectType>
 class ActionPipe {
  public:
-  virtual ~ActionPipe() {
-    LOG(INFO) << "ActionPipe died";
-  }
+  virtual ~ActionPipe() {}
 
   // This should be called by an Action on its input pipe.
   // Returns a reference to the stored object.