Revert "Revert "Upgrade to 5.0.71.48"" DO NOT MERGE

This reverts commit f2e3994fa5148cc3d9946666f0b0596290192b0e,
and updates the x64 makefile properly so it doesn't break that
build.

FPIIM-449

Change-Id: Ib83e35bfbae6af627451c926a9650ec57c045605
(cherry picked from commit 109988c7ccb6f3fd1a58574fa3dfb88beaef6632)
diff --git a/build/README.chromium b/build/README.chromium
new file mode 100644
index 0000000..012df35
--- /dev/null
+++ b/build/README.chromium
@@ -0,0 +1,15 @@
+List of property sheets to be included by projects:
+  common.vsprops
+    Not used anymore. No-op. Kept for compatibility with current projects.
+
+  debug.vsprops
+    Enables debug settings. Must be included directly in Debug configuration. Includes internal\essential.vsprops.
+
+  external_code.vsprops
+    Contains settings made to simplify usage of external (non-Google) code. It relaxes the warning levels. Should be included after debug.vsprops or release.vsprops to override their settings.
+
+  output_dll_copy.rules
+    Run to enable automatic copy of DLL when they are as an input file in a vcproj project.
+
+  release.vsprops
+    Enables release settings. Must be included directly in Release configuration. Includes internal\essential.vsprops. Also includes "internal\release_impl$(CHROME_BUILD_TYPE).vsprops". So the behavior is dependant on the CHROME_BUILD_TYPE environment variable.