Synchronously update the loading state when a load starts so that the UI will...

chrome/common/render_messages_internal.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.
 
 // This header is meant to be included in multiple passes, hence no traditional
 // header guard.
 // See ipc_message_macros.h for explanation of the macros and passes.
 
 #include <string>
 #include <vector>
@@ skipping 649 matching lines @@
 
   // Change the encoding name of the page in UI when the page has detected
   // proper encoding name.
   IPC_MESSAGE_ROUTED1(ViewHostMsg_UpdateEncoding,
                       std::wstring /* new encoding name */)
 
   // Notifies the browser that we want to show a destination url for a potential
   // action (e.g. when the user is hovering over a link).
   IPC_MESSAGE_ROUTED2(ViewHostMsg_UpdateTargetURL, int32, GURL)
 
-  // Sent when the renderer is loading a frame
-  IPC_MESSAGE_ROUTED1(ViewHostMsg_DidStartLoading, int32)
+  // Sent when the renderer starts loading the page. This corresponds to
+  // WebKit's notion of the throbber starting. Note that sometimes you may get
+  // duplicates of these during a single load.
+  IPC_MESSAGE_ROUTED0(ViewHostMsg_DidStartLoading)
 
-  // Sent when the renderer is done loading a frame
-  IPC_MESSAGE_ROUTED1(ViewHostMsg_DidStopLoading, int32)
+  // Sent when the renderer is done loading a page. This corresponds to WebKit's
+  // noption of the throbber stopping.
+  IPC_MESSAGE_ROUTED0(ViewHostMsg_DidStopLoading)
 
   // Sent when the renderer loads a resource from its memory cache.
   // The security info is non empty if the resource was originally loaded over
   // a secure connection.
   // Note: May only be sent once per URL per frame per committed load.
   IPC_MESSAGE_ROUTED4(ViewHostMsg_DidLoadResourceFromMemoryCache,
                       GURL /* url */,
                       std::string  /* frame_origin */,
                       std::string  /* main_frame_origin */,
                       std::string  /* security info */)
@@ skipping 651 matching lines @@
   // by ViewHostMsg_OpenChannelToExtension.
   IPC_MESSAGE_CONTROL2(ViewHostMsg_ExtensionPostMessage,
                        int /* port_id */,
                        std::string /* message */)
 
   // Message to show a popup menu using native cocoa controls (Mac only).
   IPC_MESSAGE_ROUTED1(ViewHostMsg_ShowPopup,
                       ViewHostMsg_ShowPopup_Params)
 
 IPC_END_MESSAGES(ViewHost)