Cleanup VersionInfo after componentization.

Remove wrapper methods around version_info free functions and directly
call them instead and fixes #include if only the component is required.

Convert VersionInfo methods to free functions (as they do not have
state) and rename GetVersionStringModifier to GetChannelString.

Rename chrome/common/{chrome_version_info => channel_info}*.

Forward-declare version_info::Channel in channel_info.h and add the
missing #include of components/version_info/version_info.h were needed.

BUG=514562

Review URL: https://codereview.chromium.org/1269773002

Cr-Commit-Position: refs/heads/master@{#341568}
diff --git a/chrome/common/metrics/version_utils.cc b/chrome/common/metrics/version_utils.cc
index 2846083..bc74100 100644
--- a/chrome/common/metrics/version_utils.cc
+++ b/chrome/common/metrics/version_utils.cc
@@ -5,6 +5,7 @@
 #include "chrome/common/metrics/version_utils.h"
 
 #include "base/logging.h"
+#include "components/version_info/version_info.h"
 #include "components/version_info/version_info_values.h"
 
 namespace metrics {