Move a bunch of child-only code from content/common to content/child

content/ppapi_plugin/ppapi_plugin_main.cc

Index: content/ppapi_plugin/ppapi_plugin_main.cc
diff --git a/content/ppapi_plugin/ppapi_plugin_main.cc b/content/ppapi_plugin/ppapi_plugin_main.cc
index 25ea26e4c6c41a57b919e86d8a86741589dd1143..384ae28f76e841807f0c74e159ae400c4d413a89 100644
--- a/content/ppapi_plugin/ppapi_plugin_main.cc
+++ b/content/ppapi_plugin/ppapi_plugin_main.cc
@@ -8,7 +8,8 @@
 #include "base/message_loop.h"
 #include "base/threading/platform_thread.h"
 #include "build/build_config.h"
-#include "content/common/child_process.h"
+#include "content/child/child_process.h"
+#include "content/common/debug_util.h"
 #include "content/common/sandbox_linux.h"
 #include "content/ppapi_plugin/ppapi_thread.h"
 #include "content/public/common/content_client.h"
@@ -54,7 +55,7 @@ int PpapiPluginMain(const MainFunctionParams& parameters) {
     if (g_target_services)
       base::debug::WaitForDebugger(2*60, false);
     else
-      ChildProcess::WaitForDebugger("Ppapi");
+      WaitForDebugger("Ppapi");
   }
 
   // Set the default locale to be the current UI language. WebKit uses ICU's