update_engine: Update libchrome APIS to r456626.

The new libchrome has been ported from Chromium and some APIs
have changed. Make necessary changes at call sites.

BUG=chromium:724678
CQ-DEPEND=CL:480928
Test: Build.

Change-Id: I4dbaea4a2a19031375a8bf2415645a4f226dab57
diff --git a/omaha_request_params_unittest.cc b/omaha_request_params_unittest.cc
index 7d4dc2d..57ecf24 100644
--- a/omaha_request_params_unittest.cc
+++ b/omaha_request_params_unittest.cc
@@ -47,7 +47,7 @@
     // Create a fresh copy of the params for each test, so there's no
     // unintended reuse of state across tests.
     params_ = OmahaRequestParams(&fake_system_state_);
-    params_.set_root(tempdir_.path().value());
+    params_.set_root(tempdir_.GetPath().value());
     SetLockDown(false);
     fake_system_state_.set_prefs(&fake_prefs_);
   }
@@ -105,7 +105,8 @@
 }
 
 TEST_F(OmahaRequestParamsTest, NoDeltasTest) {
-  ASSERT_TRUE(WriteFileString(tempdir_.path().Append(".nodelta").value(), ""));
+  ASSERT_TRUE(
+      WriteFileString(tempdir_.GetPath().Append(".nodelta").value(), ""));
   EXPECT_TRUE(params_.Init("", "", false));
   EXPECT_FALSE(params_.delta_okay());
 }
@@ -113,12 +114,12 @@
 TEST_F(OmahaRequestParamsTest, SetTargetChannelTest) {
   {
     OmahaRequestParams params(&fake_system_state_);
-    params.set_root(tempdir_.path().value());
+    params.set_root(tempdir_.GetPath().value());
     EXPECT_TRUE(params.Init("", "", false));
     EXPECT_TRUE(params.SetTargetChannel("canary-channel", false, nullptr));
     EXPECT_FALSE(params.is_powerwash_allowed());
   }
-  params_.set_root(tempdir_.path().value());
+  params_.set_root(tempdir_.GetPath().value());
   EXPECT_TRUE(params_.Init("", "", false));
   EXPECT_EQ("canary-channel", params_.target_channel());
   EXPECT_FALSE(params_.is_powerwash_allowed());
@@ -127,12 +128,12 @@
 TEST_F(OmahaRequestParamsTest, SetIsPowerwashAllowedTest) {
   {
     OmahaRequestParams params(&fake_system_state_);
-    params.set_root(tempdir_.path().value());
+    params.set_root(tempdir_.GetPath().value());
     EXPECT_TRUE(params.Init("", "", false));
     EXPECT_TRUE(params.SetTargetChannel("canary-channel", true, nullptr));
     EXPECT_TRUE(params.is_powerwash_allowed());
   }
-  params_.set_root(tempdir_.path().value());
+  params_.set_root(tempdir_.GetPath().value());
   EXPECT_TRUE(params_.Init("", "", false));
   EXPECT_EQ("canary-channel", params_.target_channel());
   EXPECT_TRUE(params_.is_powerwash_allowed());
@@ -141,7 +142,7 @@
 TEST_F(OmahaRequestParamsTest, SetTargetChannelInvalidTest) {
   {
     OmahaRequestParams params(&fake_system_state_);
-    params.set_root(tempdir_.path().value());
+    params.set_root(tempdir_.GetPath().value());
     SetLockDown(true);
     EXPECT_TRUE(params.Init("", "", false));
     string error_message;
@@ -151,7 +152,7 @@
     EXPECT_NE(string::npos, error_message.find("stable-channel"));
     EXPECT_FALSE(params.is_powerwash_allowed());
   }
-  params_.set_root(tempdir_.path().value());
+  params_.set_root(tempdir_.GetPath().value());
   EXPECT_TRUE(params_.Init("", "", false));
   EXPECT_EQ("stable-channel", params_.target_channel());
   EXPECT_FALSE(params_.is_powerwash_allowed());