Bug 1215494 - Don't set b2g.safe_mode pref in child process. r=fabrice

widget/gonk/nsAppShell.cpp

@@ -848,7 +848,9 @@ nsAppShell::nsAppShell()
     , mPowerKeyChecked(false)
 {
     gAppShell = this;
-    Preferences::SetCString("b2g.safe_mode", "unset");
+    if (XRE_IsParentProcess()) {
+        Preferences::SetCString("b2g.safe_mode", "unset");
+    }
 }
 
 nsAppShell::~nsAppShell()