Break extensions ProcessManager dependency on Runtime API

extensions/browser/process_manager.h

Index: extensions/browser/process_manager.h
diff --git a/extensions/browser/process_manager.h b/extensions/browser/process_manager.h
index 0ce67521235c1d64689e7df53eb713e47eb1bcf4..664c9420fde504a05d071e6de9a9a232722b57fa 100644
--- a/extensions/browser/process_manager.h
+++ b/extensions/browser/process_manager.h
@@ -13,6 +13,7 @@
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
 #include "base/time/time.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
@@ -32,6 +33,7 @@ namespace extensions {
 
 class Extension;
 class ExtensionHost;
+class ProcessManagerObserver;
 
 // Manages dynamic state of running Chromium extensions. There is one instance
 // of this class per Profile. OTR Profiles have a separate instance that keeps
@@ -51,6 +53,10 @@ class ProcessManager : public content::NotificationObserver {
   typedef std::set<content::RenderViewHost*> ViewSet;
   const ViewSet GetAllViews() const;
 
+  // The typical observer interface.
+  void AddObserver(ProcessManagerObserver* observer);
+  void RemoveObserver(ProcessManagerObserver* observer);
+
   // Creates a new UI-less extension instance.  Like CreateViewHost, but not
   // displayed anywhere.  Returns false if no background host can be created,
   // for example for hosted apps and extensions that aren't enabled in
@@ -238,6 +244,8 @@ class ProcessManager : public content::NotificationObserver {
   ImpulseCallbackForTesting keepalive_impulse_callback_for_testing_;
   ImpulseCallbackForTesting keepalive_impulse_decrement_callback_for_testing_;
 
+  ObserverList<ProcessManagerObserver> observer_list_;
+
   base::WeakPtrFactory<ProcessManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessManager);