Keep NaCl plugins used in app background pages alive when active.

content/public/browser/browser_ppapi_host.h

Index: content/public/browser/browser_ppapi_host.h
diff --git a/content/public/browser/browser_ppapi_host.h b/content/public/browser/browser_ppapi_host.h
index 45f997ea06b7705f62594948466ffcecab9cbb83..495ebc9ae2c5917b8d26574a05b329a2f44bdbca 100644
--- a/content/public/browser/browser_ppapi_host.h
+++ b/content/public/browser/browser_ppapi_host.h
@@ -27,16 +27,33 @@ class PpapiHost;
 
 namespace content {
 
+struct PepperRendererInstanceData;
+
 // Interface that allows components in the embedder app to talk to the
 // PpapiHost in the browser process.
 //
 // There will be one of these objects in the browser per plugin process. It
 // lives entirely on the I/O thread.
-class CONTENT_EXPORT BrowserPpapiHost {
+class CONTENT_EXPORT BrowserPpapiHost :
+    public base::RefCountedThreadSafe<BrowserPpapiHost> {
  public:
+  class Delegate {

[dmichael (off chromium), 2013/11/06 22:39:21]

How about instead having something like this on BrowserPpapiHost:
virtual void SetIdleStateChangeCallback(
    const base::Callback<void (bool, /* idle */
                               base::FilePath, /* profile_data_dir */
                               const RenderViewHost*,
                               GURL /*document_url*/)>& callback) = 0;

[scheib, 2013/11/15 01:22:17]

Done.

+   public:
+    virtual ~Delegate() {}
+
+    // Called to handle a plugin instance transitioning in or out of idle state.
+    virtual void OnIdleState(bool idle,
+                             const base::FilePath& profile_data_directory,
+                             const RenderViewHost* render_view_host,
+                             const GURL& document_url) = 0;
+  };
+
   // Creates a browser host and sets up an out-of-process proxy for an external
   // pepper plugin process.
-  static BrowserPpapiHost* CreateExternalPluginProcess(
+  // |delegate| will be owned by the BrowserPpapiHost, is optional and may be
+  // NULL, and is used only for OnIdleState for NaCl extensions.
+  static scoped_refptr<BrowserPpapiHost> CreateExternalPluginProcess(
+      Delegate* delegate,
       IPC::Sender* sender,
       ppapi::PpapiPermissions permissions,
       base::ProcessHandle plugin_child_process,