update_engine: Merge remote-tracking branch 'cros/upstream' into cros/master

Since libchrome in AOSP is ahead of CrOS I had to guard against BASE_VER in a
few places to satisfy older libchromes.

file_fetcher.cc is now needed in delta_generator.

A few unittests need to be run as root.

BUG=chromium:916593
TEST=unittest
TEST=cros_generate_update_payload
TEST=cros flash
CQ-DEPEND=CL:1399261

Change-Id: If3497549e88e559f8ecc38f414259b9c774f4a44
diff --git a/payload_consumer/download_action.cc b/payload_consumer/download_action.cc
index ab9f2e8..516a456 100644
--- a/payload_consumer/download_action.cc
+++ b/payload_consumer/download_action.cc
@@ -56,7 +56,9 @@
       delegate_(nullptr),
       p2p_sharing_fd_(-1),
       p2p_visible_(true) {
+#if BASE_VER < 576279
   base::StatisticsRecorder::Initialize();
+#endif
 }
 
 DownloadAction::~DownloadAction() {}