mandoline: Add back/forward support and UI.

components/web_view/navigation_entry.h

+// 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.
+
+#ifndef COMPONENTS_WEB_VIEW_NAVIGATION_ENTRY_H_
+#define COMPONENTS_WEB_VIEW_NAVIGATION_ENTRY_H_
+

[msw, 2015/09/04 22:05:00]

nit: include <vector> and <string>

+#include "base/basictypes.h"
+#include "mojo/services/network/public/interfaces/url_loader.mojom.h"
+
+namespace web_view {
+
+// The WebView system takes incoming mojo::URLRequests and then needs to hand
+// them off to other processes. However, moving back and forward requires

[msw, 2015/09/04 22:05:00]

Do you mean "moving back and then forward" (ie. to [bar]->[foo]->[bar], so [bar]
was the 'same' url request sent multiple times)? Perhaps clarify the comment a
bit, maybe move the last sentence to the top? Overall, consider maybe something
like "This class caches data associated with a mojo::URLRequest and vends copies
of the request for the WebView system. Copies are used for repeated navigations,
but URLRequest structs are not copyable, as they contain handles to transfer
large amounts of data between processes." Maybe describing the object as a
copyable wrapper for URLRequests would help?

+// resending the same url request multiple times. However, the URLRequest
+// struct uses handles to transfer large amounts of data between processes,
+// which makes it not copyable. This class takes the data, stores it, and then
+// vends new URLRequests on demand.
+class NavigationEntry {

[msw, 2015/09/04 22:05:00]

As we discussed, I'm surprised we don't have a more general mechanism to copy
mojo structs that contain handles... As this is the first instance, maybe set
precedent by renaming this URLRequestCloneable, URLRequestCopyable, or
URLRequestCloner, or something?

+ public:
+  NavigationEntry(mojo::URLRequestPtr incoming_mojo_request);

[msw, 2015/09/04 22:05:00]

Explicit

[msw, 2015/09/04 22:05:00]

optional nit: rename incoming_mojo_request to request or original_request?

+  ~NavigationEntry();
+
+  // Creates a new URLRequest.
+  mojo::URLRequestPtr AsURLRequest();

[msw, 2015/09/04 22:05:00]

Const function

[msw, 2015/09/04 22:05:00]

nit: rename Clone or Copy?

+
+ private:
+  // All of these are straight from mojo::URLRequest.
+  mojo::String url_;
+  mojo::String method_;
+  mojo::Array<mojo::HttpHeaderPtr> headers_;
+  uint32_t response_body_buffer_size_;
+  bool auto_follow_redirects_;
+  bool bypass_cache_;
+
+  // This is a serialized version of the data from mojo::URLRequest. We copy
+  // this data straight out of the data pipes, and then serve it any time that
+  // AsURLRequest() is called.
+  std::vector<std::string> body_;
+
+  DISALLOW_COPY_AND_ASSIGN(NavigationEntry);
+};
+
+}  // namespace web_view
+
+#endif  // COMPONENTS_WEB_VIEW_NAVIGATION_ENTRY_H_