Refactor net predictor to use ResourceThrottles

chrome/browser/net/connect_interceptor.cc

-// Copyright (c) 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.
-
-#include "chrome/browser/net/connect_interceptor.h"
-
-#include "chrome/browser/net/predictor.h"
-#include "content/public/browser/resource_request_info.h"
-#include "content/public/common/resource_type.h"
-#include "net/base/load_flags.h"
-#include "net/url_request/url_request.h"
-
-namespace chrome_browser_net {
-
-ConnectInterceptor::ConnectInterceptor(Predictor* predictor)
-    : timed_cache_(base::TimeDelta::FromSeconds(
-          Predictor::kMaxUnusedSocketLifetimeSecondsWithoutAGet)),
-      predictor_(predictor) {
-  DCHECK(predictor);
-}
-
-ConnectInterceptor::~ConnectInterceptor() {
-}
-
-void ConnectInterceptor::WitnessURLRequest(net::URLRequest* request) {
-  GURL request_scheme_host(Predictor::CanonicalizeUrl(request->url()));
-  if (request_scheme_host == GURL::EmptyGURL())
-    return;
-
-  const content::ResourceRequestInfo* info =
-      content::ResourceRequestInfo::ForRequest(request);
-  bool is_main_frame = false;
-  bool is_sub_frame = false;
-  // TODO(mmenke):  Should the predictor really be fed requests without a
-  // ResourceRequestInfo?
-  if (info) {
-    content::ResourceType resource_type = info->GetResourceType();
-    is_main_frame = (resource_type == content::RESOURCE_TYPE_MAIN_FRAME);
-    is_sub_frame = (resource_type == content::RESOURCE_TYPE_SUB_FRAME);
-  }
-
-  // Learn what URLs are likely to be needed during next startup.
-  predictor_->LearnAboutInitialNavigation(request_scheme_host);
-
-  bool redirected_host = false;
-  if (request->referrer().empty()) {
-    if (request->url() != request->original_url()) {
-      // This request was completed with a redirect.
-      GURL original_scheme_host(request->original_url().GetWithEmptyPath());
-      if (request_scheme_host != original_scheme_host) {
-        redirected_host = true;
-        // Don't learn from redirects that take path as an argument, but do
-        // learn from short-hand typing entries, such as "cnn.com" redirects to
-        // "www.cnn.com".  We can't just check for has_path(), as a mere "/"
-        // will count as a path, so we check that the path is at most a "/"
-        // (1 character long) to decide the redirect is "definitive" and has no
-        // significant path.
-        // TODO(jar): It may be ok to learn from all redirects, as the adaptive
-        // system will not respond until several identical redirects have taken
-        // place.  Hence a use of a path (that changes) wouldn't really be
-        // learned from anyway.
-        if (request->original_url().path().length() <= 1 &&
-            timed_cache_.WasRecentlySeen(original_scheme_host)) {
-          // TODO(jar): These definite redirects could be learned much faster.
-          predictor_->LearnFromNavigation(original_scheme_host,
-                                          request_scheme_host);
-        }
-      }
-    }
-  } else {
-    GURL referring_scheme_host = GURL(request->referrer()).GetWithEmptyPath();
-    // Learn about our referring URL, for use in the future.
-    if (!is_main_frame && timed_cache_.WasRecentlySeen(referring_scheme_host)) {
-      predictor_->LearnFromNavigation(referring_scheme_host,
-                                      request_scheme_host);
-    }
-    if (referring_scheme_host == request_scheme_host) {
-      // We've already made any/all predictions when we navigated to the
-      // referring host, so we can bail out here.
-      // We don't update the RecentlySeen() time because any preconnections
-      // need to be made at the first navigation (i.e., when referer was loaded)
-      // and wouldn't have waited for this current request navigation.
-      return;
-    }
-  }
-  timed_cache_.SetRecentlySeen(request_scheme_host);
-
-  // Subresources for main frames usually get predicted when we detected the
-  // main frame request - way back in RenderViewHost::Navigate.  So only handle
-  // predictions now for subresources or for redirected hosts.
-  if (is_sub_frame || redirected_host) {
-    predictor_->PredictFrameSubresources(request_scheme_host,
-                                         request->first_party_for_cookies());
-  }
-  return;
-}
-
-}  // namespace chrome_browser_net