Switch Linux Auru ports over to POSIX SHM instead of legacy SYSV SHM.

content/browser/renderer_host/render_widget_helper.cc

Index: content/browser/renderer_host/render_widget_helper.cc
===================================================================
--- content/browser/renderer_host/render_widget_helper.cc	(revision 192603)
+++ content/browser/renderer_host/render_widget_helper.cc	(working copy)
@@ -97,7 +97,7 @@
   // object, so we should not be destroyed unless pending_paints_ is empty!
   DCHECK(pending_paints_.empty());
 
-#if defined(OS_MACOSX)
+#if defined(OS_POSIX) && !defined(TOOLKIT_GTK) && !defined(OS_ANDROID)
   ClearAllocatedDIBs();
 #endif
 }
@@ -335,7 +335,7 @@
     host->CreateNewFullscreenWidget(route_id);
 }
 
-#if defined(OS_MACOSX)
+#if defined(OS_POSIX) && !defined(TOOLKIT_GTK) && !defined(OS_ANDROID)
 TransportDIB* RenderWidgetHelper::MapTransportDIB(TransportDIB::Id dib_id) {
   base::AutoLock locked(allocated_dibs_lock_);