predictors: Move the configuration of speculative prefetch to field trials.

chrome/browser/predictors/resource_prefetch_predictor_browsertest.cc

 // Copyright 2016 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 <stddef.h>
 
 #include <set>
 
 #include "base/command_line.h"
 #include "base/memory/ptr_util.h"
+#include "base/strings/string_util.h"
 #include "chrome/browser/browsing_data/browsing_data_helper.h"
 #include "chrome/browser/browsing_data/browsing_data_remover.h"
 #include "chrome/browser/browsing_data/browsing_data_remover_factory.h"
 #include "chrome/browser/predictors/resource_prefetch_predictor.h"
 #include "chrome/browser/predictors/resource_prefetch_predictor_factory.h"
 #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/tabs/tab_strip_model.h"
 #include "chrome/common/chrome_switches.h"
@@ skipping 261 matching lines @@
   GURL main_frame_url_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefetchingObserver);
 };
 
 class ResourcePrefetchPredictorBrowserTest : public InProcessBrowserTest {
  protected:
   using URLRequestSummary = ResourcePrefetchPredictor::URLRequestSummary;
 
   void SetUpCommandLine(base::CommandLine* command_line) override {
-    command_line->AppendSwitchASCII(
-        switches::kSpeculativeResourcePrefetching,
-        switches::kSpeculativeResourcePrefetchingEnabledExternal);
+    command_line->AppendSwitchASCII("force-fieldtrials", "trial/group");
+    std::string parameter = base::StringPrintf(
+        "trial.group:%s/%s", kModeParamName, kExternalPrefetchingMode);
+    command_line->AppendSwitchASCII("force-fieldtrial-params", parameter);
+    std::string enabled_feature = base::StringPrintf(
+        "%s<trial", kSpeculativeResourcePrefetchingFeatureName);
+    command_line->AppendSwitchASCII("enable-features", enabled_feature);
   }
 
   void SetUpOnMainThread() override {
     // Resolving all hosts to local allows us to have
     // cross domains navigations (matching url_visit_count_, etc).
     host_resolver()->AddRule("*", "127.0.0.1");
     embedded_test_server()->RegisterRequestHandler(
         base::Bind(&ResourcePrefetchPredictorBrowserTest::HandleRedirectRequest,
                    base::Unretained(this)));
     embedded_test_server()->RegisterRequestHandler(
@@ skipping 562 matching lines @@
   TryToPrefetchURL(initial_url);
   NavigateToURLAndCheckSubresources(initial_url);
   ClearCache();
   // But the predictor database contains all subresources for the endpoint url
   // so this prefetch works.
   PrefetchURL(GetURL(kHtmlSubresourcesPath));
   NavigateToURLAndCheckSubresourcesAllCached(GetURL(kHtmlSubresourcesPath));
 }
 
 }  // namespace predictors