Cleanup: merging three different constants.h into a single header.

remoting/base/constants.cc

Index: remoting/base/constants.cc
diff --git a/remoting/base/constants.cc b/remoting/base/constants.cc
index a93f0f4aa84d764ab9196ec742f06d97354ff0a9..d693af29d580d3166fedea5baca39f4850125bca 100644
--- a/remoting/base/constants.cc
+++ b/remoting/base/constants.cc
@@ -21,4 +21,11 @@ const char kVideoRtcpChannelName[] = "videortpc";
 
 const char kMimeTypeTextUtf8[] = "text/plain; charset=UTF-8";
 
+#if defined(OS_WIN)
+// The Omaha Appid of the host. It should be kept in sync with $(var.OmahaAppid)
+// defined in remoting/host/installer/chromoting.wxs and the Omaha server
+// configuration.
+const wchar_t kHostOmahaAppid[] = L"{b210701e-ffc4-49e3-932b-370728c72662}";
+#endif  // defined(OS_WIN)
+
 }  // namespace remoting