Restructure SDCH layering to allow more separation (observer/1->[0,n]

chrome/browser/net/chrome_sdch_policy.cc

+// Copyright 2014 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.
+
+#include "chrome/browser/net/chrome_sdch_policy.h"
+
+#include "base/bind.h"
+#include "net/base/sdch_manager.h"
+
+ChromeSdchPolicy::ChromeSdchPolicy(net::SdchManager* sdch_manager,
+                                   net::URLRequestContext* context)
+    : manager_(sdch_manager),
+      // Because |fetcher_| is owned by ChromeSdchPolicy, the
+      // ChromeSdchPolicy object will be available for the lifetime
+      // of |fetcher_|.

[Ryan Sleevi, 2014/11/04 21:40:44]

1) I'm not sure what this comment is communicating that isn't "obvious" from the
code
.. but also

2) Is this true if fetcher_ were to PostTask something, and then this object
were deleted? The posted task would still be on the queue, indicating that a
WeakPtr should be used. Which then messes things up vis-a-vis WeakPtrFactory
(since the factory must be last), meaning you'd probably need fetcher_ to be
scoped_ptr rather than member.

Just the initial reaction from this code (not having dug into fetcher_ yet)

[Randy Smith (Not in Mondays), 2014/11/05 20:35:01]

Ok, just being over-paranoid about documenting ownership lifetimes.  Deleted. 
All true, but not a problem, since fetcher doesn't PostTask anything, which
behavior is specified and guaranteed in the constructor interface comment.

+      fetcher_(context, base::Bind(&ChromeSdchPolicy::OnDictionaryFetched,
+                                   base::Unretained(this))) {
+  manager_->AddObserver(this);
+}
+
+ChromeSdchPolicy::~ChromeSdchPolicy() {
+  manager_->RemoveObserver(this);
+}
+
+void ChromeSdchPolicy::OnDictionaryFetched(const std::string& dictionary_text,
+                         const GURL& dictionary_url) {
+  manager_->AddSdchDictionary(dictionary_text, dictionary_url);
+}
+
+void ChromeSdchPolicy::OnGetDictionary(net::SdchManager* manager,
+                                       const GURL& request_url,
+                                       const GURL& dictionary_url) {
+  fetcher_.Schedule(dictionary_url);
+}
+
+void ChromeSdchPolicy::OnClearDictionaries(net::SdchManager* manager) {
+  fetcher_.Cancel();
+}