Wire up process launch error codes.

content/browser/child_process_launcher.h

Index: content/browser/child_process_launcher.h
diff --git a/content/browser/child_process_launcher.h b/content/browser/child_process_launcher.h
index 710247778bbfb56b16e971fd2f69d7e21c40375e..edb1761893460bd8c286dabb70adf56f88dc5787 100644
--- a/content/browser/child_process_launcher.h
+++ b/content/browser/child_process_launcher.h
@@ -24,6 +24,19 @@ class CommandLine;
 
 namespace content {
 
+// Platform neutral result codes for process launches.
+// Each platform can optionally define its own specific set of error codes.
+// For Windows, these are sandbox::ResultCode starting at offset 1000 located in

[jam, 2016/04/28 15:41:14]

normally this is done by having the lower layer set an enum for max value it
needs (with some room to leave for further growth if it's in UMA). then content
etc can start its values there. i understand sandbox' enum is only on windows,
but it seems fine to have this enum here have an ifdef to start it at that value
(1000) on windows, otherwise it starts at 0. that way sandbox doesn't have to
keep the assumption that content etc won't use more than a thousand values.

[Will Harris, 2016/05/02 16:45:23]

I now start the enum in the lower layer, and then continue it up in content.

I added a static assert to verify that the ranges can never overlap, since I
can't just start at the end of sandbox (since that's a Win only header file).

+// sandbox/win/src/sandbox_types.h
+enum LaunchResultCode {
+  // Launch success.
+  LAUNCH_RESULT_SUCCESS = 0,
+  // Generic launch failure.
+  LAUNCH_RESULT_FAILURE,
+  // Placeholder for last item of the enum.
+  LAUNCH_RESULT_CODE_LAST_CODE
+};
+
 // Launches a process asynchronously and notifies the client of the process
 // handle when it's available.  It's used to avoid blocking the calling thread
 // on the OS since often it can take > 100 ms to create the process.
@@ -35,7 +48,7 @@ class CONTENT_EXPORT ChildProcessLauncher : public base::NonThreadSafe {
     // constructed on.
     virtual void OnProcessLaunched() = 0;
 
-    virtual void OnProcessLaunchFailed() {};
+    virtual void OnProcessLaunchFailed(int error_code) {};
 
    protected:
     virtual ~Client() {}
@@ -101,14 +114,16 @@ class CONTENT_EXPORT ChildProcessLauncher : public base::NonThreadSafe {
                         base::ScopedFD ipcfd,
                         base::ScopedFD mojo_fd,
 #endif
-                        base::Process process);
+                        base::Process process,
+                        int error_code);
 
   // Notifies the client about the result of the operation.
   void Notify(ZygoteHandle zygote,
 #if defined(OS_ANDROID)
               base::ScopedFD ipcfd,
 #endif
-              base::Process process);
+              base::Process process,
+              int error_code);
 
 #if defined(MOJO_SHELL_CLIENT)
   // When this process is run from an external Mojo shell, this function will