predictors: Add subresources count and prefetching duration histograms.

chrome/browser/predictors/resource_prefetch_predictor.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/predictors/resource_prefetch_predictor.h"
 
 #include <map>
 #include <set>
 #include <utility>
 
@@ skipping 132 matching lines @@
   size_t precision_percentage =
       (100 * correctly_predicted_count) / predicted_urls_set.size();
   size_t recall_percentage =
       (100 * correctly_predicted_count) / actual_urls_set.size();
 
   UMA_HISTOGRAM_PERCENTAGE(
       internal::kResourcePrefetchPredictorPrecisionHistogram,
       precision_percentage);
   UMA_HISTOGRAM_PERCENTAGE(internal::kResourcePrefetchPredictorRecallHistogram,
                            recall_percentage);
+  UMA_HISTOGRAM_COUNTS_100(internal::kResourcePrefetchPredictorCountHistogram,
+                           predicted_urls.size());
 }
 
 }  // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
 // ResourcePrefetchPredictor static functions.
 
 // static
 bool ResourcePrefetchPredictor::ShouldRecordRequest(
     net::URLRequest* request,
@@ skipping 336 matching lines @@
     default:
       NOTREACHED() << "Unexpected initialization_state_: "
                    << initialization_state_;
   }
 }
 
 void ResourcePrefetchPredictor::StartPrefetching(const GURL& url,
                                                  PrefetchOrigin origin) {
   TRACE_EVENT1("browser", "ResourcePrefetchPredictor::StartPrefetching", "url",
                url.spec());
+  // Save prefetch start time to report prefetching duration.
+  if (inflight_prefetchings_.find(url) == inflight_prefetchings_.end() &&
+      IsUrlPrefetchable(url)) {
+    inflight_prefetchings_.insert(std::make_pair(url, base::TimeTicks::Now()));
+  }
+
   if (!prefetch_manager_.get())  // Prefetching not enabled.
     return;
   if (!config_.IsPrefetchingEnabledForOrigin(profile_, origin))
     return;
 
   std::vector<GURL> subresource_urls;
   if (!GetPrefetchData(url, &subresource_urls))
     return;
 
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&ResourcePrefetcherManager::MaybeAddPrefetch,
                  prefetch_manager_, url, subresource_urls));
 }
 
 void ResourcePrefetchPredictor::StopPrefetching(const GURL& url) {
   TRACE_EVENT1("browser", "ResourcePrefetchPredictor::StopPrefetching", "url",
                url.spec());
+  std::map<GURL, base::TimeTicks>::iterator prefetching_it =
+      inflight_prefetchings_.find(url);
+  if (prefetching_it != inflight_prefetchings_.end()) {
+    UMA_HISTOGRAM_TIMES(
+        internal::kResourcePrefetchPredictorPrefetchingDurationHistogram,
+        base::TimeTicks::Now() - prefetching_it->second);
+    inflight_prefetchings_.erase(prefetching_it);
+  }
   if (!prefetch_manager_.get())  // Not enabled.
     return;
 
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&ResourcePrefetcherManager::MaybeRemovePrefetch,
                  prefetch_manager_, url));
 }
 
 void ResourcePrefetchPredictor::OnPrefetchingFinished(
@@ skipping 225 matching lines @@
   base::TimeTicks time_now = base::TimeTicks::Now();
   for (NavigationMap::iterator it = inflight_navigations_.begin();
        it != inflight_navigations_.end();) {
     if ((it->first.tab_id == navigation_id.tab_id) ||
         (time_now - it->first.creation_time > max_navigation_age)) {
       inflight_navigations_.erase(it++);
     } else {
       ++it;
     }
   }
+
+  for (std::map<GURL, base::TimeTicks>::iterator it =
+           inflight_prefetchings_.begin();
+       it != inflight_prefetchings_.end();) {
+    if (time_now - it->second > max_navigation_age)
+      inflight_prefetchings_.erase(it++);
+    else
+      ++it;
+  }
 }
 
 void ResourcePrefetchPredictor::DeleteAllUrls() {
   inflight_navigations_.clear();
   url_table_cache_->clear();
   host_table_cache_->clear();
   url_redirect_table_cache_->clear();
   host_redirect_table_cache_->clear();
 
   BrowserThread::PostTask(BrowserThread::DB, FROM_HERE,
@@ skipping 459 matching lines @@
 TestObserver::~TestObserver() {
   predictor_->SetObserverForTesting(nullptr);
 }
 
 TestObserver::TestObserver(ResourcePrefetchPredictor* predictor)
     : predictor_(predictor) {
   predictor_->SetObserverForTesting(this);
 }
 
 }  // namespace predictors