update_engine: Reflect ActionProcessor and UpdateBootFlags changes in AOSP

We changed the ActionProcessor interface and how we update boot flags in
CL:1065113 and CL:1011244. This patch reflects those changes in
update_attempter_android.*

BUG=chromium:807976
TEST=unittests
TEST=build and run in android

Change-Id: Ib06b6c1560e58771e66288208a525130a5811360
Reviewed-on: https://chromium-review.googlesource.com/1150737
Commit-Ready: Amin Hassani <ahassani@chromium.org>
Tested-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Sen Jiang <senj@chromium.org>
diff --git a/common/action_processor_unittest.cc b/common/action_processor_unittest.cc
index b67eca9..eb646ef 100644
--- a/common/action_processor_unittest.cc
+++ b/common/action_processor_unittest.cc
@@ -166,7 +166,7 @@
   action_processor_.EnqueueAction(std::move(action1));
   action_processor_.EnqueueAction(std::move(action2));
 
-  EXPECT_EQ(action_processor_.actions_.size(), 3);
+  EXPECT_EQ(action_processor_.actions_.size(), 3u);
   EXPECT_EQ(action_processor_.actions_[0].get(), action0_ptr);
   EXPECT_EQ(action_processor_.actions_[1].get(), action1_ptr);
   EXPECT_EQ(action_processor_.actions_[2].get(), action2_ptr);