bug 539552 - Forward-declare CrashGenerationServer from client_info.h. r=ted

--HG--
extra : transplant_source : %CC%A0%BF%3D%B7%0A%13%8D%F3%E9x%1B%14%F6US%E0%F6%BB%9B

toolkit/crashreporter/google-breakpad/src/client/linux/crash_generation/client_info.h

@@ -32,6 +32,8 @@
 
 namespace google_breakpad {
 
+class CrashGenerationServer;
+
 struct ClientInfo {
   CrashGenerationServer* crash_server_;
   pid_t pid_;