AU: Optimize checkpointing a bit and decide on new update vs. resume.

install_plan.h

Index: install_plan.h
diff --git a/install_plan.h b/install_plan.h
index 19fee8a2add02312b6cc583cb3552c83043bf3ef..8dc42aa722f973d29226ed3a73c0651f41023be5 100644
--- a/install_plan.h
+++ b/install_plan.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -15,20 +15,23 @@ namespace chromeos_update_engine {
 
 struct InstallPlan {
   InstallPlan(bool is_full,
+              bool is_resume,
               const std::string& url,
               uint64_t size,
               const std::string& hash,
               const std::string& install_path,
               const std::string& kernel_install_path)
       : is_full_update(is_full),
+        is_resume(is_resume),
         download_url(url),
         size(size),
         download_hash(hash),
         install_path(install_path),
         kernel_install_path(kernel_install_path) {}
-  InstallPlan() : is_full_update(false) {}
+  InstallPlan() : is_full_update(false), is_resume(false), size(0) {}
 
   bool is_full_update;
+  bool is_resume;
   std::string download_url;  // url to download from
   uint64_t size;  // size of the download url's data
   std::string download_hash;  // hash of the data at the url
@@ -37,11 +40,12 @@ struct InstallPlan {
 
   bool operator==(const InstallPlan& that) const {
     return (is_full_update == that.is_full_update) &&
-           (download_url == that.download_url) &&
-           (size == that.size) &&
-           (download_hash == that.download_hash) &&
-           (install_path == that.install_path) &&
-           (kernel_install_path == that.kernel_install_path);
+        (is_resume == that.is_resume) &&
+        (download_url == that.download_url) &&
+        (size == that.size) &&
+        (download_hash == that.download_hash) &&
+        (install_path == that.install_path) &&
+        (kernel_install_path == that.kernel_install_path);
   }
   bool operator!=(const InstallPlan& that) const {
     return !((*this) == that);
@@ -49,6 +53,7 @@ struct InstallPlan {
   void Dump() const {
     LOG(INFO) << "InstallPlan: "
               << (is_full_update ? "full_update" : "delta_update")
+              << (is_resume ? ", resume" : ", new_update")
               << ", url: " << download_url
               << ", size: " << size
               << ", hash: " << download_hash