Forward handling of low-mem message to the content renderer client. Add APIs to handle this case.

chrome/renderer/chrome_render_process_observer.h

Index: chrome/renderer/chrome_render_process_observer.h
diff --git a/chrome/renderer/chrome_render_process_observer.h b/chrome/renderer/chrome_render_process_observer.h
index beb2b2687932571f7ab1f068b8b5f36c40d14140..936129015c90d4c0bc7bf7800bad7a75ac815756 100644
--- a/chrome/renderer/chrome_render_process_observer.h
+++ b/chrome/renderer/chrome_render_process_observer.h
@@ -12,6 +12,10 @@
 #include "base/memory/scoped_ptr.h"
 #include "content/renderer/render_process_observer.h"
 
+namespace chrome {
+class ChromeContentRendererClient;
+}
+
 class GURL;
 class ResourceDispatcherDelegate;
 struct ContentSettings;
@@ -22,7 +26,8 @@ struct ContentSettings;
 // observer.
 class ChromeRenderProcessObserver : public RenderProcessObserver {
  public:
-  ChromeRenderProcessObserver();
+  explicit ChromeRenderProcessObserver(
+      chrome::ChromeContentRendererClient* client);
   virtual ~ChromeRenderProcessObserver();
 
   static bool is_incognito_process() { return is_incognito_process_; }
@@ -49,6 +54,7 @@ class ChromeRenderProcessObserver : public RenderProcessObserver {
 
   static bool is_incognito_process_;
   scoped_ptr<ResourceDispatcherDelegate> resource_delegate_;
+  chrome::ChromeContentRendererClient* client_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeRenderProcessObserver);
 };