Adds speculative prefetching of resources.

chrome/browser/predictors/resource_prefetcher_manager.cc

+// Copyright (c) 2012 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/predictors/resource_prefetcher_manager.h"
+
+#include "base/bind.h"
+#include "base/stl_util.h"
+#include "chrome/browser/predictors/resource_prefetch_predictor.h"
+#include "content/public/browser/browser_thread.h"
+#include "net/url_request/url_request.h"
+#include "net/url_request/url_request_context_getter.h"
+
+using content::BrowserThread;
+
+namespace predictors {
+
+ResourcePrefetcherManager::ResourcePrefetcherManager(
+    ResourcePrefetchPredictor* predcitor,

[dominich, 2012/08/02 15:00:50]

nit: predictor

[Shishir, 2012/08/02 22:06:54]

Done.

+    const ResourcePrefetchPredictorConfig& config,
+    net::URLRequestContextGetter* context_getter)
+    : predictor_(predcitor),
+      config_(config),
+      context_getter_(context_getter),
+      prefetcher_map_deleter_(&prefetcher_map_) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  CHECK(predictor_);
+  CHECK(context_getter_);
+}
+
+ResourcePrefetcherManager::~ResourcePrefetcherManager() {
+}
+
+void ResourcePrefetcherManager::ShutdownOnUIThread() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  predictor_ = NULL;
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+      base::Bind(&ResourcePrefetcherManager::ShutdownOnIOThread,
+                 this));
+}
+
+void ResourcePrefetcherManager::ShutdownOnIOThread() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+}
+
+void ResourcePrefetcherManager::MaybeAddPrefetch(
+    const NavigationID& navigation_id,
+    scoped_ptr<ResourcePrefetcher::RequestVector> requests) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  const GURL& main_frame_url = navigation_id.main_frame_url;
+  if (prefetcher_map_.find(main_frame_url) != prefetcher_map_.end())

[dominich, 2012/08/02 15:00:50]

Avoiding the double lookup:

PrefetcherMap::iterator prefetcher_it = prefetcher_map_.find(main_frame_url);
if (it != prefetcher_map_.end())
  return;

ResourcePrefetcher* prefetcher = new ResourcePrefetcher(
    this, config_, navigation_id, requests.Pass());
prefetcher_map_.insert(std::make_pair(main_frame_url, prefetcher));
prefetcher->Start();
    main_frame_url,
        

[Shishir, 2012/08/02 22:06:54]

Done.

+    return;
+
+  ResourcePrefetcher* prefetcher = new ResourcePrefetcher(
+      this, config_, navigation_id, requests.Pass());
+  prefetcher_map_[main_frame_url] = prefetcher;
+  prefetcher->Start();
+}
+
+void ResourcePrefetcherManager::MaybeRemovePrefetch(
+    const NavigationID& navigation_id) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  PrefetcherMap::iterator it = prefetcher_map_.find(
+      navigation_id.main_frame_url);
+  if (it != prefetcher_map_.end() &&
+      it->second->navigation_id() == navigation_id) {
+    it->second->Stop();
+  }
+}
+
+void ResourcePrefetcherManager::ResourcePrefetcherFinished(
+    ResourcePrefetcher* resource_prefetcher,
+    ResourcePrefetcher::RequestVector* requests) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  // 'predictor_' can only be accessed from the UI thread.

[dominich, 2012/08/02 15:00:50]

nit: variable refs in comments use || in chromium style

[Shishir, 2012/08/02 22:06:54]

Done.

+  scoped_ptr<ResourcePrefetcher::RequestVector> requests_ptr(requests);
+  BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+      base::Bind(&ResourcePrefetcherManager::ResourcePrefetcherFinishedOnUI,
+                 this,
+                 resource_prefetcher->navigation_id(),
+                 base::Passed(requests_ptr.Pass())));

[dominich, 2012/08/02 15:00:50]

i believe &requests_ptr might be less verbose

[Shishir, 2012/08/02 22:06:54]

Ah syntactic sugar.

+
+  const GURL& main_frame_url =
+      resource_prefetcher->navigation_id().main_frame_url;
+  PrefetcherMap::iterator it = prefetcher_map_.find(main_frame_url);
+  DCHECK(it != prefetcher_map_.end());
+  delete it->second;
+  prefetcher_map_.erase(main_frame_url);
+}
+
+void ResourcePrefetcherManager::ResourcePrefetcherFinishedOnUI(
+    const NavigationID& navigation_id,
+    scoped_ptr<ResourcePrefetcher::RequestVector> requests) {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  // Notify the 'predictor_'.

[dominich, 2012/08/02 15:00:50]

nit: variable name in comment uses ||

[Shishir, 2012/08/02 22:06:54]

Done.

+  if (predictor_)
+    predictor_->FinishedPrefetchForNavigation(navigation_id,
+                                              requests.Pass());
+}
+
+net::URLRequestContext* ResourcePrefetcherManager::GetURLRequestContext() {
+  CHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  return context_getter_->GetURLRequestContext();
+}
+
+}  // namespace predictors