Browser Plugin: Implement CanGoBack/CanGoForward

content/common/browser_plugin_messages.h

Index: content/common/browser_plugin_messages.h
diff --git a/content/common/browser_plugin_messages.h b/content/common/browser_plugin_messages.h
index 6bc5154b13372c0566e61d2e4b36ac9d39d54971..0ceec54b43a02abe2f945ba4d1af30b2f4cc0d5c 100644
--- a/content/common/browser_plugin_messages.h
+++ b/content/common/browser_plugin_messages.h
@@ -135,6 +135,15 @@ IPC_SYNC_MESSAGE_ROUTED2_0(BrowserPluginHostMsg_ResizeGuest,
 // -----------------------------------------------------------------------------
 // These messages are from the browser process to the embedder.
 
+// When the guest navigates any of its frames, it reports to the browser plugin
+// the current state of navigation history so that that information can be
+// queried from Javascript.
+IPC_MESSAGE_CONTROL3(BrowserPluginMsg_NavigationStateUpdate,
+                     int /* instance_id */,
+                     bool /* current_entry_index */,
+                     int /* entry_count */)
+
+
 // When the guest begins to load a page, the browser process informs the
 // embedder through the BrowserPluginMsg_LoadStart message.
 IPC_MESSAGE_CONTROL3(BrowserPluginMsg_LoadStart,