Navigation transitions: Pass is_transition_navigation flag up to the embedder

content/common/frame_messages.h

 // Copyright 2013 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.
 
 // IPC messages for interacting with frames.
 // Multiply-included message file, hence no include guard.
 
 #include "content/common/content_export.h"
 #include "content/common/content_param_traits.h"
 #include "content/common/frame_message_enums.h"
@@ skipping 420 matching lines @@
                             int32 /* new_routing_id */)
 
 // Sent by the renderer to the parent RenderFrameHost when a child frame is
 // detached from the DOM.
 IPC_MESSAGE_ROUTED0(FrameHostMsg_Detach)
 
 // Sent by the renderer when the frame becomes focused.
 IPC_MESSAGE_ROUTED0(FrameHostMsg_FrameFocused)
 
 // Sent when the renderer starts a provisional load for a frame.
-IPC_MESSAGE_ROUTED1(FrameHostMsg_DidStartProvisionalLoadForFrame,
-                    GURL /* url */)
+// |is_transition_navigation| signals that the frame has defined transition
+// elements which can be animated by the navigation destination to provide
+// a transition effect during load.
+IPC_MESSAGE_ROUTED2(FrameHostMsg_DidStartProvisionalLoadForFrame,
+                    GURL /* url */,
+                    bool /* is_transition_navigation */)
 
 // Sent when the renderer fails a provisional load with an error.
 IPC_MESSAGE_ROUTED1(FrameHostMsg_DidFailProvisionalLoadWithError,
                     FrameHostMsg_DidFailProvisionalLoadWithError_Params)
 
 // Sent when a provisional load on the main frame redirects.
 IPC_MESSAGE_ROUTED3(FrameHostMsg_DidRedirectProvisionalLoad,
                     int /* page_id */,
                     GURL /* source_url*/,
                     GURL /* target_url */)
@@ skipping 228 matching lines @@
                      int /* render_frame_id */,
                      bool /* is_transition */)
 
 // Tells the browser to perform a navigation.
 IPC_MESSAGE_ROUTED1(FrameHostMsg_BeginNavigation,
                     FrameHostMsg_BeginNavigation_Params)
 
 // Sent once a paint happens after the first non empty layout. In other words
 // after the frame has painted something.
 IPC_MESSAGE_ROUTED0(FrameHostMsg_DidFirstVisuallyNonEmptyPaint)