predictors: Add prefetching hit/miss histograms.

chrome/browser/predictors/resource_prefetcher_unittest.cc

Index: chrome/browser/predictors/resource_prefetcher_unittest.cc
diff --git a/chrome/browser/predictors/resource_prefetcher_unittest.cc b/chrome/browser/predictors/resource_prefetcher_unittest.cc
index a412b552bcdab7ea207a15af92f6deee54fdc0f5..7b51d949f1c7f812c9868c4c8f7494f91236f0a2 100644
--- a/chrome/browser/predictors/resource_prefetcher_unittest.cc
+++ b/chrome/browser/predictors/resource_prefetcher_unittest.cc
@@ -61,17 +61,27 @@ class TestResourcePrefetcherDelegate : public ResourcePrefetcher::Delegate {
   explicit TestResourcePrefetcherDelegate(base::MessageLoop* loop)
       : request_context_getter_(
             new net::TestURLRequestContextGetter(loop->task_runner())) {}
-  ~TestResourcePrefetcherDelegate() { }
+  ~TestResourcePrefetcherDelegate() override {}
 
   net::URLRequestContext* GetURLRequestContext() override {
     return request_context_getter_->GetURLRequestContext();
   }
 
-  MOCK_METHOD1(ResourcePrefetcherFinished,
-               void(ResourcePrefetcher* prefetcher));
+  void ResourcePrefetcherFinished(
+      ResourcePrefetcher* prefetcher,
+      std::unique_ptr<ResourcePrefetcher::PrefetcherStats> stats) override {
+    prefetcher_ = prefetcher;
+  }
+
+  bool ResourcePrefetcherFinishedCalled(ResourcePrefetcher* for_prefetcher) {
+    ResourcePrefetcher* prefetcher = prefetcher_;
+    prefetcher_ = nullptr;
+    return prefetcher == for_prefetcher;
+  }
 
  private:
   scoped_refptr<net::TestURLRequestContextGetter> request_context_getter_;
+  ResourcePrefetcher* prefetcher_;
 
   DISALLOW_COPY_AND_ASSIGN(TestResourcePrefetcherDelegate);
 };
@@ -221,8 +231,8 @@ TEST_F(ResourcePrefetcherTest, TestPrefetcherFinishes) {
   CheckPrefetcherState(1, 0, 1);
 
   // Expect the final call.
-  EXPECT_CALL(prefetcher_delegate_,
-              ResourcePrefetcherFinished(Eq(prefetcher_.get())));
+  EXPECT_TRUE(

[alexilin, 2017/02/13 17:07:05]

This test fails.

EXPECT_CALL introduces assert that will be checked after test execution, but
your assert must be true at the call time.

You could move assert after the last OnResponse() that actually calls Delegate
or you could check assertion in a destructor of TestResourcePrefetcherDelegate.

[Benoit L, 2017/02/13 17:32:51]

Done.

+      prefetcher_delegate_.ResourcePrefetcherFinishedCalled(prefetcher_.get()));
 
   OnResponse("http://yahoo.com/resource3.png");
   CheckPrefetcherState(0, 0, 0);
@@ -265,8 +275,8 @@ TEST_F(ResourcePrefetcherTest, TestPrefetcherStopped) {
   CheckPrefetcherState(1, 1, 1);
 
   // Expect the final call.
-  EXPECT_CALL(prefetcher_delegate_,
-              ResourcePrefetcherFinished(Eq(prefetcher_.get())));
+  EXPECT_TRUE(
+      prefetcher_delegate_.ResourcePrefetcherFinishedCalled(prefetcher_.get()));
 
   OnResponse("http://m.google.com/resource1.jpg");
   CheckPrefetcherState(0, 1, 0);
@@ -311,8 +321,8 @@ TEST_F(ResourcePrefetcherTest, TestHistogramsCollected) {
       internal::kResourcePrefetchPredictorCachePatternHistogram, 1);
 
   // Expect the final call.
-  EXPECT_CALL(prefetcher_delegate_,
-              ResourcePrefetcherFinished(Eq(prefetcher_.get())));
+  EXPECT_TRUE(
+      prefetcher_delegate_.ResourcePrefetcherFinishedCalled(prefetcher_.get()));
 
   OnResponse("http://www.google.com/resource6.png");
   histogram_tester.ExpectTotalCount(