predictors: Add trace events to the resource_prefetch_predictor.

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>
 
 #include "base/command_line.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "base/time/time.h"
+#include "base/trace_event/trace_event.h"
 #include "chrome/browser/history/history_service_factory.h"
 #include "chrome/browser/predictors/predictor_database.h"
 #include "chrome/browser/predictors/predictor_database_factory.h"
 #include "chrome/browser/predictors/resource_prefetcher_manager.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.h"
 #include "components/history/core/browser/history_database.h"
 #include "components/history/core/browser/history_service.h"
 #include "components/mime_util/mime_util.h"
@@ skipping 550 matching lines @@
             config_.min_resource_hits_to_trigger_prefetch)
       continue;
 
     urls->push_back(GURL(resource.resource_url()));
   }
 
   return urls->size() > initial_size;
 }
 
 void ResourcePrefetchPredictor::StartPrefetching(const GURL& url) {
+  TRACE_EVENT1("browser", "ResourcePrefetchPredictor::StartPrefetching", "url",

[pasko, 2016/10/14 15:59:47]

traces in category "browser" generally look less relevant than "loader", up to
you, I am not feeling strongly about this choice

+               url.spec());
   if (!prefetch_manager_.get())  // Prefetching not enabled.
     return;
 
   std::vector<GURL> subresource_urls;
   if (!GetPrefetchData(url, &subresource_urls)) {
     // No prefetching data at host or URL level.
     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());
   if (!prefetch_manager_.get())  // Not enabled.
     return;
 
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&ResourcePrefetcherManager::MaybeRemovePrefetch,
                  prefetch_manager_, url));
 }
 
 void ResourcePrefetchPredictor::StartInitialization() {
@@ skipping 225 matching lines @@
 }
 
 void ResourcePrefetchPredictor::LearnNavigation(
     const std::string& key,
     PrefetchKeyType key_type,
     const std::vector<URLRequestSummary>& new_resources,
     size_t max_data_map_size,
     PrefetchDataMap* data_map,
     const std::string& key_before_redirects,
     RedirectDataMap* redirect_map) {
+  TRACE_EVENT1("browser", "ResourcePrefetchPredictor::LearnNavigation", "key",
+               key);
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 
   // If the primary key is too long reject it.
   if (key.length() > ResourcePrefetchPredictorTables::kMaxStringLength)
     return;
 
   PrefetchDataMap::iterator cache_entry = data_map->find(key);
   if (cache_entry == data_map->end()) {
     // If the table is full, delete an entry.
     if (data_map->size() >= max_data_map_size)
@@ skipping 257 matching lines @@
     // HistoryService is already loaded. Continue with Initialization.
     OnHistoryAndCacheLoaded();
     return;
   }
   DCHECK(!history_service_observer_.IsObserving(history_service));
   history_service_observer_.Add(history_service);
   return;
 }
 
 }  // namespace predictors