Group renderer processes by privilige when we hit the max process count....

chrome/browser/renderer_host/render_process_host.h

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_RENDERER_HOST_RENDER_PROCESS_HOST_H_
 #define CHROME_BROWSER_RENDERER_HOST_RENDER_PROCESS_HOST_H_
 
 #include <set>
 #include <string>
 
@@ skipping 10 matching lines @@
 // RenderProcessHost per renderer process.
 //
 // The concrete implementation of this class for normal use is the
 // BrowserRenderProcessHost. It may also be implemented by a testing interface
 // for mocking purposes.
 class RenderProcessHost : public IPC::Channel::Sender,
                           public IPC::Channel::Listener {
  public:
   typedef IDMap<RenderProcessHost>::const_iterator iterator;
 
+  // We classify renderers according to their highest privilege, and try
+  // to group pages into renderers with similar privileges.
+  // Note: it may be possible for a renderer to have multiple privileges,
+  // in which case we call it an "extension" renderer.
+  enum Type {
+    TYPE_NORMAL,     // Normal renderer, no extra privileges.
+    TYPE_DOMUI,      // Renderer with DOMUI privileges, like New Tab.
+    TYPE_EXTENSION,  // Renderer with extension privileges.
+  };
+
   RenderProcessHost(Profile* profile);
   virtual ~RenderProcessHost();
 
   // Returns the user profile associated with this renderer process.
   Profile* profile() const { return profile_; }
 
   // Returns the process id for this host. This can be used later in
   // a call to FromID() to get back to this object (this is used to avoid
   // sending non-threadsafe pointers to other threads).
   int pid() const { return pid_; }
@@ skipping 126 matching lines @@
 
   // Returns the RenderProcessHost given its ID.  Returns NULL if the ID does
   // not correspond to a live RenderProcessHost.
   static RenderProcessHost* FromID(int render_process_id);
 
   // Returns true if the caller should attempt to use an existing
   // RenderProcessHost rather than creating a new one.
   static bool ShouldTryToUseExistingProcessHost();
 
   // Get an existing RenderProcessHost associated with the given profile, if
-  // possible.  The renderer process is chosen randomly from the
-  // processes associated with the given profile.
-  // Returns NULL if no suitable renderer process is available.
-  static RenderProcessHost* GetExistingProcessHost(Profile* profile);
+  // possible.  The renderer process is chosen randomly from suitable renderers
+  // that share the same profile and type.
+  // Returns NULL if no suitable renderer process is available, in which case
+  // the caller is free to create a new renderer.
+  static RenderProcessHost* GetExistingProcessHost(Profile* profile, Type type);
 
  protected:
-  // Sets the process  of this object, so that others access it using FromID.
+  // Sets the process of this object, so that others access it using FromID.
   void SetProcessID(int pid);
 
+  // For testing.  Removes this host from the list of hosts.
+  void RemoveFromList();
+
   base::Process process_;
 
   // A proxy for our IPC::Channel that lives on the IO thread (see
   // browser_process.h)
   scoped_ptr<IPC::SyncChannel> channel_;
 
   // the registered listeners. When this list is empty or all NULL, we should
   // delete ourselves
   IDMap<IPC::Channel::Listener> listeners_;
 
@@ skipping 25 matching lines @@
 // Factory object for RenderProcessHosts. Using this factory allows tests to
 // swap out a different one to use a TestRenderProcessHost.
 class RenderProcessHostFactory {
  public:
   virtual ~RenderProcessHostFactory() {}
   virtual RenderProcessHost* CreateRenderProcessHost(
       Profile* profile) const = 0;
 };
 
 #endif  // CHROME_BROWSER_RENDERER_HOST_RENDER_PROCESS_HOST_H_