Don't send components version if changing to more stable channel.

When changing to more stable channel and powerwash is allowed, we send
0.0.0.0 as version to Omaha to get an update right away, but there're
also version information in the product components, so we should just
not send those in this case.
Also fixed cpplint warnings in the file touched by this CL.

Test: update_engine_unittests
Change-Id: If43a8dce79d6f59a609cd3306190be3d05dab296
diff --git a/omaha_request_params.h b/omaha_request_params.h
index 6284ee1..a9215ae 100644
--- a/omaha_request_params.h
+++ b/omaha_request_params.h
@@ -133,6 +133,9 @@
   inline std::string product_components() const {
     return image_props_.product_components;
   }
+  inline void set_product_components(const std::string& product_components) {
+    image_props_.product_components = product_components;
+  }
 
   inline std::string current_channel() const {
     return image_props_.current_channel;