Fix a crash seen at times when chrome in desktop mode attempts to activate Chrome in Windows 8 mode…

win8/metro_driver/chrome_url_launch_handler.cc

Index: win8/metro_driver/chrome_url_launch_handler.cc
===================================================================
--- win8/metro_driver/chrome_url_launch_handler.cc	(revision 161954)
+++ win8/metro_driver/chrome_url_launch_handler.cc	(working copy)
@@ -102,6 +102,10 @@
 // are encoded in |launch_args| they are ignored.
 string16 ChromeUrlLaunchHandler::GetUrlFromLaunchArgs(
     const string16& launch_args) {
+  if (launch_args == L"opennewwindow") {
+    VLOG(1) << "Returning new tab url";
+    return L"chrome://newtab";
+  }
   string16 dummy_command_line(L"dummy.exe ");
   dummy_command_line.append(launch_args);
   CommandLine command_line = CommandLine::FromString(dummy_command_line);
@@ -179,6 +183,11 @@
   DVLOG(1) << (url ? url : L"NULL url");
   DVLOG(1) << (search_string ? search_string : L"NULL search string");
 
+  if (globals.host_windows.empty()) {
+    DVLOG(1) << "No chrome windows registered. Ignoring nav request";
+    return;
+  }
+
   // Custom registered message to navigate or search in chrome. WPARAM
   // points to the URL and LPARAM contains the search string. They are
   // mutually exclusive.