Provide renderers with memory pressure signals.

chrome/browser/memory/tab_stats.h

Index: chrome/browser/memory/tab_stats.h
diff --git a/chrome/browser/memory/tab_stats.h b/chrome/browser/memory/tab_stats.h
index 33a8a8b0b89884797a97e06869cc727ec4e388c1..8c6b48a35793aa566ea356d424c9809976b88325 100644
--- a/chrome/browser/memory/tab_stats.h
+++ b/chrome/browser/memory/tab_stats.h
@@ -14,6 +14,10 @@
 #include "base/time/time.h"
 #include "build/build_config.h"
 
+namespace content {
+class RenderProcessHost;
+}  // namespace content
+
 namespace memory {
 
 struct TabStats {
@@ -28,6 +32,7 @@ struct TabStats {
   bool has_form_entry;  // User has entered text in a form.
   int discard_count;
   base::TimeTicks last_active;
+  content::RenderProcessHost* render_process_host;
   base::ProcessHandle renderer_handle;
   int child_process_host_id;
   base::string16 title;