predictors: Add browsertest that tests prefetching.

chrome/browser/predictors/resource_prefetch_predictor_browsertest.cc

Index: chrome/browser/predictors/resource_prefetch_predictor_browsertest.cc
diff --git a/chrome/browser/predictors/resource_prefetch_predictor_browsertest.cc b/chrome/browser/predictors/resource_prefetch_predictor_browsertest.cc
index 91e3d93786e17c3e8a87925d0a4301fed1fa73b3..1780355b4d4ccbe0c6d9ff4ee995392640d2fa9c 100644
--- a/chrome/browser/predictors/resource_prefetch_predictor_browsertest.cc
+++ b/chrome/browser/predictors/resource_prefetch_predictor_browsertest.cc
@@ -8,6 +8,7 @@
 #include "chrome/browser/predictors/resource_prefetch_predictor_test_util.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/browser_commands.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/test/base/in_process_browser_test.h"
@@ -112,14 +113,13 @@ std::vector<URLRequestSummary> GetUniqueSubresources(
 // Helper class to track and allow waiting for ResourcePrefetchPredictor events.
 // These events are also used to verify that ResourcePrefetchPredictor works as
 // expected.
-class ResourcePrefetchPredictorTestObserver : public TestObserver {
+class LearningObserver : public TestObserver {
  public:
   using PageRequestSummary = ResourcePrefetchPredictor::PageRequestSummary;
 
-  explicit ResourcePrefetchPredictorTestObserver(
-      ResourcePrefetchPredictor* predictor,
-      const size_t expected_url_visit_count,
-      const PageRequestSummary& expected_summary)
+  explicit LearningObserver(ResourcePrefetchPredictor* predictor,
+                            const size_t expected_url_visit_count,
+                            const PageRequestSummary& expected_summary)
       : TestObserver(predictor),
         url_visit_count_(expected_url_visit_count),
         summary_(expected_summary) {}
@@ -146,7 +146,33 @@ class ResourcePrefetchPredictorTestObserver : public TestObserver {
   size_t url_visit_count_;
   PageRequestSummary summary_;
 
-  DISALLOW_COPY_AND_ASSIGN(ResourcePrefetchPredictorTestObserver);
+  DISALLOW_COPY_AND_ASSIGN(LearningObserver);
+};
+
+class PrefetchingObserver : public TestObserver {
+ public:
+  explicit PrefetchingObserver(ResourcePrefetchPredictor* predictor,
+                               const GURL& expected_main_frame_url)
+      : TestObserver(predictor), main_frame_url_(expected_main_frame_url) {}
+
+  // TestObserver:
+  void OnNavigationLearned(size_t url_visit_count,
+                           const PageRequestSummary& summary) override {
+    ADD_FAILURE() << "Prefetching shouldn't activate learning";
+  }
+
+  void OnPrefetchingFinished(const GURL& main_frame_url) override {
+    EXPECT_EQ(main_frame_url_, main_frame_url);
+    run_loop_.Quit();
+  }
+
+  void Wait() { run_loop_.Run(); }
+
+ private:
+  base::RunLoop run_loop_;
+  GURL main_frame_url_;
+
+  DISALLOW_COPY_AND_ASSIGN(PrefetchingObserver);
 };
 
 class ResourcePrefetchPredictorBrowserTest : public InProcessBrowserTest {
@@ -182,12 +208,26 @@ class ResourcePrefetchPredictorBrowserTest : public InProcessBrowserTest {
       url_request_summaries.push_back(
           GetURLRequestSummaryForResource(endpoint_url, kv.second));
     }
-    ResourcePrefetchPredictorTestObserver observer(
+    LearningObserver observer(
         predictor_, UpdateAndGetVisitCount(main_frame_url),
         CreatePageRequestSummary(endpoint_url.spec(), main_frame_url.spec(),
                                  url_request_summaries));
     ui_test_utils::NavigateToURL(browser(), main_frame_url);
     observer.Wait();
+    for (auto& kv : resources_) {
+      if (!kv.second.is_no_store && kv.second.should_be_recorded)
+        kv.second.request.was_cached = true;
+    }
+  }
+
+  void PrefetchURL(const GURL& main_frame_url) {
+    PrefetchingObserver observer(predictor_, main_frame_url);
+    predictor_->StartPrefetching(main_frame_url, PrefetchOrigin::NAVIGATION);
+    observer.Wait();
+    for (auto& kv : resources_) {
+      if (!kv.second.is_no_store && kv.second.should_be_recorded)
+        kv.second.request.was_cached = true;
+    }
   }
 
   ResourceSummary* AddResource(const GURL& resource_url,
@@ -233,6 +273,12 @@ class ResourcePrefetchPredictorBrowserTest : public InProcessBrowserTest {
     }
   }
 
+  void ClearCache() {
+    chrome::ClearCache(browser());
+    for (auto& kv : resources_)
+      kv.second.request.was_cached = false;
+  }
+
   // Shortcut for convenience.
   GURL GetURL(const std::string& path) const {
     return embedded_test_server()->GetURL(path);
@@ -489,4 +535,21 @@ IN_PROC_BROWSER_TEST_F(ResourcePrefetchPredictorBrowserTest,
   NavigateToURLAndCheckSubresources(GetURL(kHtmlIframePath));
 }
 
+IN_PROC_BROWSER_TEST_F(ResourcePrefetchPredictorBrowserTest,
+                       PrefetchingSimple) {
+  AddResource(GetURL(kImagePath), content::RESOURCE_TYPE_IMAGE, net::LOWEST);
+  AddResource(GetURL(kStylePath), content::RESOURCE_TYPE_STYLESHEET,
+              net::HIGHEST);
+  AddResource(GetURL(kScriptPath), content::RESOURCE_TYPE_SCRIPT, net::MEDIUM);
+  AddResource(GetURL(kFontPath), content::RESOURCE_TYPE_FONT_RESOURCE,
+              net::HIGHEST);
+  // We need to have at least two resource hits to trigger prefetch.
+  NavigateToURLAndCheckSubresources(GetURL(kHtmlSubresourcesPath));
+  ClearCache();
+  NavigateToURLAndCheckSubresources(GetURL(kHtmlSubresourcesPath));
+  ClearCache();
+  PrefetchURL(GetURL(kHtmlSubresourcesPath));
+  NavigateToURLAndCheckSubresources(GetURL(kHtmlSubresourcesPath));

[alexilin, 2016/12/06 12:44:17]

Here we reuse interceptors of URLRequests that ResourcePrefetchPredictor has and
check that all resources has actually been served from cache.

+}
+
 }  // namespace predictors