[Panels refactor] Track Panels in TaskManager now that they are not under the tab contents umbrella.

chrome/browser/ui/panels/panel.h

Index: chrome/browser/ui/panels/panel.h
diff --git a/chrome/browser/ui/panels/panel.h b/chrome/browser/ui/panels/panel.h
index 4a3d15db8a1e7e5c98bd76e2f9728746f7db8b03..e2afe1ddd02ae7ade18af8a89a42fbbe178a07a6 100644
--- a/chrome/browser/ui/panels/panel.h
+++ b/chrome/browser/ui/panels/panel.h
@@ -9,6 +9,7 @@
 
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/property_bag.h"
 #include "base/string16.h"
 #include "chrome/browser/command_updater.h"
 #include "chrome/browser/sessions/session_id.h"
@@ -69,6 +70,14 @@ class Panel : public BaseWindow,
 
   virtual ~Panel();
 
+  // Helper to retrieve the existing instance that owns a given WebContents.
+  // Returns NULL if there is no such existing instance.
+  // NOTE: This is not intended for general use. It is intended for situations
+  // like callbacks from content, where only a WebContents is available. In the
+  // general case, please do NOT use this; plumb Panels through the chrome/
+  // code instead of WebContents.
+  static Panel* FromWebContents(content::WebContents* contents);
+
   // Returns the PanelManager associated with this panel.
   PanelManager* manager() const;
 
@@ -310,6 +319,10 @@ class Panel : public BaseWindow,
   friend class PanelBrowserTest;
   friend class OldPanelBrowserTest;
 
+  // Used to retrieve this object from the web_contents, which is placed in
+  // the web contents property bag to avoid adding additional interfaces.
+  static base::PropertyAccessor<Panel*>* property_accessor();
+
   enum MaxSizePolicy {
     // Default maximum size is proportional to the work area.
     DEFAULT_MAX_SIZE,