predictors: move ResourcePrefetcher handling to LoadingPredictor.

chrome/browser/predictors/loading_predictor.h

Index: chrome/browser/predictors/loading_predictor.h
diff --git a/chrome/browser/predictors/loading_predictor.h b/chrome/browser/predictors/loading_predictor.h
index 89f48bb407b630e6186b440795610738deab34e1..2aa3f6768548f182c5919c95852bbc393f9b49ac 100644
--- a/chrome/browser/predictors/loading_predictor.h
+++ b/chrome/browser/predictors/loading_predictor.h
@@ -7,6 +7,7 @@
 
 #include <map>
 #include <memory>
+#include <string>
 #include <utility>
 
 #include "base/gtest_prod_util.h"
@@ -15,6 +16,8 @@
 #include "chrome/browser/predictors/loading_data_collector.h"
 #include "chrome/browser/predictors/resource_prefetch_common.h"
 #include "chrome/browser/predictors/resource_prefetch_predictor.h"
+#include "chrome/browser/predictors/resource_prefetcher.h"
+#include "chrome/browser/profiles/profile.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "url/gurl.h"
 
@@ -24,6 +27,7 @@ namespace predictors {
 
 class ResourcePrefetchPredictor;
 class LoadingStatsCollector;
+class TestLoadingObserver;
 
 // Entry point for the Loading predictor.
 // From a high-level request (GURL and motivation) and a database of historical
@@ -36,7 +40,8 @@ class LoadingStatsCollector;
 // predictor.
 //
 // All methods must be called from the UI thread.
-class LoadingPredictor : public KeyedService {
+class LoadingPredictor : public KeyedService,
+                         public ResourcePrefetcher::Delegate {
  public:
   LoadingPredictor(const LoadingPredictorConfig& config, Profile* profile);
   ~LoadingPredictor() override;
@@ -69,6 +74,16 @@ class LoadingPredictor : public KeyedService {
     return weak_factory_.GetWeakPtr();
   }
 
+  // ResourcePrefetcher::Delegate:
+  void ResourcePrefetcherFinished(
+      ResourcePrefetcher* prefetcher,
+      std::unique_ptr<ResourcePrefetcher::PrefetcherStats> stats) override;
+
+  // Sets the |observer| to be notified when prefetches start and
+  // finish. A previously registered observer will be discarded. Call this with
+  // a nullptr parameter to de-register the observer.
+  void SetObserverForTesting(TestLoadingObserver* observer);
+
  private:
   // Cancels an active hint, from its iterator inside |active_hints_|. If the
   // iterator is .end(), does nothing. Returns the iterator after deletion of
@@ -77,6 +92,16 @@ class LoadingPredictor : public KeyedService {
       std::map<GURL, base::TimeTicks>::iterator hint_it);
   void CleanupAbandonedHintsAndNavigations(const NavigationID& navigation_id);
 
+  // May start a prefetch for |url| with the data from |prediction|, and a
+  // given hint |origin|. A new prefetch may not start if there is already
+  // one in flight, for instance.
+  void MaybeAddPrefetch(const GURL& url,
+                        const ResourcePrefetchPredictor::Prediction& prediction,
+                        HintOrigin origin);
+
+  // If a prefetch exists for |url|, stop it.
+  void MaybeRemovePrefetch(const GURL& url);
+
   // For testing.
   void set_mock_resource_prefetch_predictor(
       std::unique_ptr<ResourcePrefetchPredictor> predictor) {
@@ -91,6 +116,10 @@ class LoadingPredictor : public KeyedService {
   std::map<GURL, base::TimeTicks> active_hints_;
   // Initial URL.
   std::map<NavigationID, GURL> active_navigations_;
+  // The value is {prefetcher, already deleted}.
+  std::map<std::string, std::pair<std::unique_ptr<ResourcePrefetcher>, bool>>
+      prefetches_;

[alexilin, 2017/07/03 14:55:02]

I think |active_navigations_| and |prefetches_| could be merged, I don't see a
reason for them to have entries with different lifetimes.
Feel free to leave it as is. I'm going to change it in following CLs anyway.

[Benoit L, 2017/07/03 15:43:15]

It does not seem entirely clear to me that merging them is nicer than leaving
them separate, so I defer to your forthcoming CL.

+  TestLoadingObserver* observer_;
 
   friend class LoadingPredictorTest;
   FRIEND_TEST_ALL_PREFIXES(LoadingPredictorTest,
@@ -109,6 +138,30 @@ class LoadingPredictor : public KeyedService {
   DISALLOW_COPY_AND_ASSIGN(LoadingPredictor);
 };
 
+// An interface used to notify that data in the LoadingPredictor has
+// changed. All methods are called on the UI thread.
+class TestLoadingObserver {
+ public:
+  // De-registers itself from |predictor_| on destruction.
+  virtual ~TestLoadingObserver();
+
+  virtual void OnPrefetchingStarted(const GURL& main_frame_url) {}
+
+  virtual void OnPrefetchingStopped(const GURL& main_frame_url) {}
+
+  virtual void OnPrefetchingFinished(const GURL& main_frame_url) {}
+
+ protected:
+  // |predictor| must be non-NULL and has to outlive the LoadingTestObserver.
+  // Also the predictor must not have a LoadingTestObserver set.
+  explicit TestLoadingObserver(LoadingPredictor* predictor);
+
+ private:
+  LoadingPredictor* predictor_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestLoadingObserver);
+};
+
 }  // namespace predictors
 
 #endif  // CHROME_BROWSER_PREDICTORS_LOADING_PREDICTOR_H_