Fix OmahaRequest unittests in Brillo.

Moved lsb_release related tests to ImagePropertiesTest.

Bug: 26955860
Test: GTEST_FILTER="Omaha*" ./update_engine_unittests
Test: cros_workon_make update_engine --test

Change-Id: I124c9374e7556b04c65bdac80e1b89064dee4008
diff --git a/omaha_request_params.h b/omaha_request_params.h
index b4534a1..379563a 100644
--- a/omaha_request_params.h
+++ b/omaha_request_params.h
@@ -106,6 +106,10 @@
   inline std::string canary_app_id() const {
     return image_props_.canary_product_id;
   }
+  inline void set_app_id(const std::string& app_id) {
+    image_props_.product_id = app_id;
+    image_props_.canary_product_id = app_id;
+  }
   inline std::string app_lang() const { return app_lang_; }
   inline std::string hwid() const { return hwid_; }
   inline std::string fw_version() const { return fw_version_; }
@@ -236,9 +240,8 @@
 
  private:
   FRIEND_TEST(OmahaRequestParamsTest, IsValidChannelTest);
-  FRIEND_TEST(OmahaRequestParamsTest, ShouldLockDownTest);
   FRIEND_TEST(OmahaRequestParamsTest, ChannelIndexTest);
-  FRIEND_TEST(OmahaRequestParamsTest, LsbPreserveTest);
+  FRIEND_TEST(OmahaRequestParamsTest, ToMoreStableChannelFlagTest);
   FRIEND_TEST(OmahaRequestParamsTest, CollectECFWVersionsTest);
 
   // Returns true if |channel| is a valid channel, false otherwise.