OOPIFs: Transitioning MHTML generation from view-oriented to frame-oriented.

content/common/frame_messages.h

Index: content/common/frame_messages.h
diff --git a/content/common/frame_messages.h b/content/common/frame_messages.h
index 72d675141671f3b92c3f4cb8d3a5ed4c11adafbc..23d68cafff10c2802d5cbd4a5259477dd22ee667 100644
--- a/content/common/frame_messages.h
+++ b/content/common/frame_messages.h
@@ -29,6 +29,7 @@
 #include "content/public/common/three_d_api_types.h"
 #include "content/public/common/transition_element.h"
 #include "ipc/ipc_message_macros.h"
+#include "ipc/ipc_platform_file.h"
 #include "third_party/WebKit/public/platform/WebFocusType.h"
 #include "third_party/WebKit/public/web/WebFrameOwnerProperties.h"
 #include "third_party/WebKit/public/web/WebTreeScopeType.h"
@@ -720,6 +721,31 @@ using FrameMsg_GetSerializedHtmlWithLocalLinks_Map =
 IPC_MESSAGE_ROUTED1(FrameMsg_GetSerializedHtmlWithLocalLinks,
                     FrameMsg_GetSerializedHtmlWithLocalLinks_Map);
 
+// Serialize target frame and its resources into MHTML and write it into the
+// provided destination file handle.
+//
+// When starting generation of a new MHTML document, one needs to start by
+// sending FrameMsg_SerializeAsMHTML for the *main* frame (main frame needs to
+// be the first part in the MHTML document + main frame will trigger generation
+// of the MHTML header).
+//
+// The same |mhtml_boundary_marker| should be used for serialization of each
+// frame (this string will be used as a mime multipart boundary within the mhtml
+// document).
+//
+// For more details about frame to content id map please see
+// WebPageSerializer::generateMHTMLParts method.
+//
+// |is_last_frame| controls whether the serializer in the renderer will
+// emit the MHTML footer.

[Randy Smith (Not in Mondays), 2015/12/10 23:07:55]

nit, suggestion/question: Why not emit the header/footer from the browser
process and keep the IPC interface simpler?

[lukasza, 2015/12/11 00:29:03]

I wasn't sure about that, but it felt better to keep all the MHTML
parsing/generation code (and test code) close together in Blink.

[ncarter (slow), 2015/12/11 17:21:42]

Also, you can't do file IO on the UI thread where the coordination code lives,
so you'd have to farm it off on the file thread or the blocking pool, and that's
more complicated than just getting the child process to do it.

[Randy Smith (Not in Mondays), 2015/12/14 02:47:04]

Acknowledged.

[Randy Smith (Not in Mondays), 2015/12/14 02:47:04]

Acknowledged.

+using FrameRoutingIdToContentIdMap = std::map<int, std::string>;
+IPC_MESSAGE_ROUTED5(FrameMsg_SerializeAsMHTML,
+                    int /* job_id (used to match responses to requests) */,
+                    IPC::PlatformFileForTransit /* destination file handle */,
+                    std::string /* mhtml boundary marker */,
+                    FrameRoutingIdToContentIdMap,
+                    bool /* is last frame */)
+
 IPC_MESSAGE_ROUTED1(FrameMsg_SetFrameOwnerProperties,
                     blink::WebFrameOwnerProperties /* frame_owner_properties */)
 
@@ -1244,6 +1270,11 @@ IPC_MESSAGE_ROUTED2(FrameHostMsg_SerializedHtmlWithLocalLinksResponse,
                     std::string /* data buffer */,
                     bool /* end of data? */)
 
+// Response to FrameMsg_SerializeAsMHTML.
+IPC_MESSAGE_ROUTED2(FrameHostMsg_SerializeAsMHTMLResponse,
+                    int /* job_id (used to match responses to requests) */,
+                    bool /* true if success, false if error */)
+
 // Sent when the renderer updates hint for importance of a tab.
 IPC_MESSAGE_ROUTED1(FrameHostMsg_UpdatePageImportanceSignals,
                     content::PageImportanceSignals)