Replace image_messages.h with Mojo service

content/common/image_downloader/image_downloader_types.mojom

Index: content/common/image_downloader/image_downloader_types.mojom
diff --git a/content/common/image_downloader/image_downloader_types.mojom b/content/common/image_downloader/image_downloader_types.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..fb0e3630ac22fe20c00e8ddcb6ce3c79a18630b3
--- /dev/null
+++ b/content/common/image_downloader/image_downloader_types.mojom
@@ -0,0 +1,23 @@
+// Copyright 2015 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.
+
+module image_downloader;
+
+import "third_party/mojo_services/src/geometry/public/interfaces/geometry.mojom";
+import "skia/public/interfaces/bitmap.mojom";
+
+struct DownloadReq {

[Ken Rockot(use gerrit already), 2015/04/14 16:14:20]

nit: I think we shouldn't abbreviate this. DownloadRequest would be fine.

Alternatively since these live in image_downloader, they could also just be
Request and Result respectively.

[Anand Mistry (off Chromium), 2015/04/16 01:07:16]

I too think these should live in image_downloader.mojom. They're not generally
useful by themselves, so no point in splitting them out.

[leonhsl(Using Gerrit), 2015/04/17 06:14:34]

Done. 
Combine image_downloader_types.mojom into image_downloader.mojom.
Struct name as DownloadRequest/DownloadResult.

+  string url;
+  bool is_favicon;
+  uint32 max_bitmap_size;
+  bool bypass_cache;
+};
+
+struct DownloadResult {
+  int32 http_status_code;

[Anand Mistry (off Chromium), 2015/04/16 01:07:16]

uint32. HTTP status codes are defined to be 3-digit integers
(http://tools.ietf.org/html/rfc7231#page-47), and hence are always non-negative.

[leonhsl(Using Gerrit), 2015/04/17 06:14:34]

The old IPC message ImageHostMsg_DidDownloadImage defines http status code as
int32, and codes residing in both sides of the ImageDownloader mojo connection
are treating it as int32, because int32 is also enough to hold the 3-digit
integer, can we just keep it now? Otherwise we need to align many places to
uint32.

+  string url;

[Anand Mistry (off Chromium), 2015/04/16 01:07:16]

Why is this needed? As far as I can tell, it never changes and is just passed
from request to response.

[leonhsl(Using Gerrit), 2015/04/17 06:14:34]

Done. Yes we can omit it from response.

+  array<skia.Bitmap> images;
+  array<mojo.Size> original_image_sizes;
+};
+