Use irt from within chrome install

visual_studio/NativeClientVSAddIn/NativeClientVSAddIn/PluginDebuggerGDB.cs

Index: visual_studio/NativeClientVSAddIn/NativeClientVSAddIn/PluginDebuggerGDB.cs
diff --git a/visual_studio/NativeClientVSAddIn/NativeClientVSAddIn/PluginDebuggerGDB.cs b/visual_studio/NativeClientVSAddIn/NativeClientVSAddIn/PluginDebuggerGDB.cs
index f4cebfe179bd270e6cd4bec86e72f39459e4cbc8..704d70c3a4e5b5de2e29dc28f8fe24e596c579c5 100644
--- a/visual_studio/NativeClientVSAddIn/NativeClientVSAddIn/PluginDebuggerGDB.cs
+++ b/visual_studio/NativeClientVSAddIn/NativeClientVSAddIn/PluginDebuggerGDB.cs
@@ -8,6 +8,7 @@ namespace NativeClientVSAddIn
   using System.IO;
   using System.Text;
   using System.Windows.Forms;
+  using System.Diagnostics;
 
   using EnvDTE;
   using EnvDTE80;
@@ -60,7 +61,21 @@ namespace NativeClientVSAddIn
     public PluginDebuggerGDB(DTE2 dte, PropertyManager properties)
         : base(dte, properties)
     {
-      irtPath_ = properties.IrtPath;
+      string arch = "x86_32";
+      if (Environment.Is64BitOperatingSystem)
+      {
+        arch = "x86_64";
+      }
+      string chrome_path = properties.LocalDebuggerCommand;
+      FileVersionInfo version_info = FileVersionInfo.GetVersionInfo(chrome_path);
+      string file_version = version_info.FileVersion;
+      irtPath_ = Path.Combine(Path.GetDirectoryName(chrome_path), file_version, "nacl_irt_" + arch + ".nexe");
+      if (!File.Exists(irtPath_))
+      {
+        MessageBox.Show("NaCL IRT not found in chrome install.\nLooking for: " + irtPath_);
+        irtPath_ = null;
+      }
+
       manifestPath_ = properties.ManifestPath;
       pluginAssembly_ = properties.PluginAssembly;
       pluginProjectDirectory_ = properties.ProjectDirectory;
@@ -162,8 +177,14 @@ namespace NativeClientVSAddIn
         contents.AppendFormat("file \"{0}\"\n", pluginAssemblyEscaped);
       }
 
-      string irtPathEscaped = irtPath_.Replace("\\", "\\\\");
-      contents.AppendFormat("nacl-irt {0}\n", irtPathEscaped);
+      // irtPath_ could be null if the irt nexe was not found in the chrome
+      // install.
+      if (irtPath_ != null)
+      {
+        string irtPathEscaped = irtPath_.Replace("\\", "\\\\");
+        contents.AppendFormat("nacl-irt \"{0}\"\n", irtPathEscaped);
+      }
+
       contents.AppendFormat("target remote localhost:{0}\n", 4014);
 
       // Insert breakpoints from Visual Studio project.