[downloads] Set initiator when handling downloads via a[download]

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 <stddef.h>
 #include <stdint.h>
 
@@ skipping 19 matching lines @@
 #include "content/public/common/common_param_traits.h"
 #include "content/public/common/console_message_level.h"
 #include "content/public/common/context_menu_params.h"
 #include "content/public/common/file_chooser_file_info.h"
 #include "content/public/common/file_chooser_params.h"
 #include "content/public/common/form_field_data.h"
 #include "content/public/common/frame_navigate_params.h"
 #include "content/public/common/javascript_message_type.h"
 #include "content/public/common/page_importance_signals.h"
 #include "content/public/common/page_state.h"
+#include "content/public/common/referrer.h"
 #include "content/public/common/resource_response.h"
 #include "content/public/common/stop_find_action.h"
 #include "content/public/common/three_d_api_types.h"
 #include "ipc/ipc_message_macros.h"
 #include "ipc/ipc_platform_file.h"
 #include "ppapi/features/features.h"
 #include "third_party/WebKit/public/platform/WebFocusType.h"
 #include "third_party/WebKit/public/platform/WebInsecureRequestPolicy.h"
 #include "third_party/WebKit/public/web/WebFindOptions.h"
 #include "third_party/WebKit/public/web/WebFrameOwnerProperties.h"
@@ skipping 367 matching lines @@
   IPC_STRUCT_MEMBER(scoped_refptr<content::ResourceRequestBodyImpl>,
                     resource_request_body)
   IPC_STRUCT_MEMBER(std::string, extra_headers)
   IPC_STRUCT_MEMBER(content::Referrer, referrer)
   IPC_STRUCT_MEMBER(WindowOpenDisposition, disposition)
   IPC_STRUCT_MEMBER(bool, should_replace_current_entry)
   IPC_STRUCT_MEMBER(bool, user_gesture)
   IPC_STRUCT_MEMBER(bool, is_history_navigation_in_new_child)
 IPC_STRUCT_END()
 
+IPC_STRUCT_BEGIN(FrameHostMsg_DownloadUrl_Params)
+  IPC_STRUCT_MEMBER(int, render_view_id)
+  IPC_STRUCT_MEMBER(int, render_frame_id)
+  IPC_STRUCT_MEMBER(GURL, url)
+  IPC_STRUCT_MEMBER(content::Referrer, referrer)
+  IPC_STRUCT_MEMBER(url::Origin, initiator_origin)

[clamy, 2016/12/14 16:25:38]

Should this be an Optional<url::Origin>, considering that it will be put in an
Optional<url::Origin> and that we're setting all initiators transmitted from the
renderer as optional?

[asanka, 2016/12/14 18:21:30]

The intent is that URLRequest::initiator() and in turn
DownloadUrlParameters::initiator() can be optional, but DownloadUrl requests
coming from a renderer *must* have an initiator_origin. If one is unavailable,
we'd end up with a unique origin which has subtly different semantics than a
null origin. I.e. a unique initiator would result in no SameSite cookies being
sent while a null initiator may result in SameSite=Lax cookies being sent for
safe methods.

mkwest: Is the above reasonable? Should a renderer be able to initiate a
download with a null initiator origin? I intentionally made it not so.

There are other users of the DownloadUrlParameters API (a.k.a.
DownloadManager::DownloadURL() API). These should be able to make requests
without specifying an initiator since there may not always be one. E.g. a
programmatic download initiated by Chrome itself wouldn't have an initiator
origin.

+  IPC_STRUCT_MEMBER(base::string16, suggested_name)
+IPC_STRUCT_END()
+
 IPC_STRUCT_BEGIN(FrameMsg_TextTrackSettings_Params)
   // Text tracks on/off state
   IPC_STRUCT_MEMBER(bool, text_tracks_enabled)
 
   // Background color of the text track.
   IPC_STRUCT_MEMBER(std::string, text_track_background_color)
 
   // Font family of the text track text.
   IPC_STRUCT_MEMBER(std::string, text_track_font_family)
 
@@ skipping 585 matching lines @@
 // If a cross-process navigation was started for the initial history load in
 // this subframe, this tries to cancel it to allow a client redirect to happen
 // instead.
 IPC_MESSAGE_ROUTED0(FrameHostMsg_CancelInitialHistoryLoad)
 
 // Notifies the browser that a frame finished loading.
 IPC_MESSAGE_ROUTED1(FrameHostMsg_DidFinishLoad,
                     GURL /* validated_url */)
 
 // Initiates a download based on user actions like 'ALT+click'.
-IPC_MESSAGE_CONTROL5(FrameHostMsg_DownloadUrl,
-                     int /* render_view_id */,
-                     int /* render_frame_id */,
-                     GURL /* url */,
-                     content::Referrer /* referrer */,
-                     base::string16 /* suggested_name */)
+IPC_MESSAGE_CONTROL(FrameHostMsg_DownloadUrl, FrameHostMsg_DownloadUrl_Params)
 
 // Asks the browser to save a image (for <canvas> or <img>) from a data URL.
 // Note: |data_url| is the contents of a data:URL, and that it's represented as
 // a string only to work around size limitations for GURLs in IPC messages.
 IPC_MESSAGE_CONTROL3(FrameHostMsg_SaveImageFromDataURL,
                      int /* render_view_id */,
                      int /* render_frame_id */,
                      std::string /* data_url */)
 
 // Sent when after the onload handler has been invoked for the document
@@ skipping 465 matching lines @@
 // nearest find result in the sending frame.
 IPC_MESSAGE_ROUTED2(FrameHostMsg_GetNearestFindResult_Reply,
                     int /* nfr_request_id */,
                     float /* distance */)
 #endif
 
 // Adding a new message? Stick to the sort order above: first platform
 // independent FrameMsg, then ifdefs for platform specific FrameMsg, then
 // platform independent FrameHostMsg, then ifdefs for platform specific
 // FrameHostMsg.