Make the browser->metro_viewer IPC channel name a constant instead of hardcoding it in a few places…

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 706c1e7656266d3ee1f89ac7b329e82730916282..18d1cb1534a1bcca7c8c9b59db0bd446a5c1be4a 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -1481,10 +1481,6 @@ const char kVariationsServerURL[]           = "variations-server-url";
 // Prints version information and quits.
 const char kVersion[]                       = "version";
 
-// Requests that Chrome connect to a remote viewer process using an IPC
-// channel of the given name.
-const char kViewerConnection[]              = "viewer-connection";
-
 // Cycle through a series of URLs listed in the specified file.
 const char kVisitURLs[]                     = "visit-urls";
 
@@ -1605,6 +1601,11 @@ const char kWindows8Search[]           = "windows8-search";
 
 #endif
 
+#if defined(OS_WIN) && defined(USE_AURA)
+// Requests that Chrome connect to the running Metro viewer process.
+const char kViewerConnect[]                 = "viewer-connect";
+#endif
+
 #ifndef NDEBUG
 // Enables overriding the path of file manager extension.
 const char kFileManagerExtensionPath[]      = "filemgr-ext-path";