Enable SpeculativePreconnect Field Trial Testing

The predictors::kSpeculativePreconnectFeature is explicitly disabled in
net::Predictor browser tests because the LoadingPredictor if enabled
intercepts all prefetch and preconnect coming from a renderer.

WarmupManagerTest.testPreconnect() was expecting two connections to be
opened but it's not the case for the LoadingPredictor, it opens only
one connection.

Bug: 699080
Change-Id: I73537c3a59818793e41c5741762fe675a4efa97f
Reviewed-on: https://chromium-review.googlesource.com/754837Reviewed-by: Ted Choc <tedchoc@chromium.org>
Reviewed-by: Helen Li <xunjieli@chromium.org>
Reviewed-by: Jesse Doherty <jwd@chromium.org>
Commit-Queue: Alexandr Ilin <alexilin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515502}

chrome/android/javatests/src/org/chromium/chrome/browser/WarmupManagerTest.java

@@ -202,9 +202,9 @@ public class WarmupManagerTest {
     public void testPreconnect() throws Exception {
         EmbeddedTestServer server = new EmbeddedTestServer();
         try {
-            // The predictor prepares 2 connections when asked to preconnect. Initializes the
-            // semaphore to be unlocked after 2 connections.
-            final Semaphore connectionsSemaphore = new Semaphore(1 - 2);
+            // The predictor prepares 1 connection when asked to preconnect. Initializes the
+            // semaphore to be unlocked after 1 connection.
+            final Semaphore connectionsSemaphore = new Semaphore(0);
 
             // Cannot use EmbeddedTestServer#createAndStartServer(), as we need to add the
             // connection listener.
@@ -224,7 +224,7 @@ public class WarmupManagerTest {
             if (!connectionsSemaphore.tryAcquire(5, TimeUnit.SECONDS)) {
                 // Starts at -1.
                 int actualConnections = connectionsSemaphore.availablePermits() + 1;
-                Assert.fail("Expected 2 connections, got " + actualConnections);
+                Assert.fail("Expected 1 connection, got " + actualConnections);
             }
         } finally {
             server.stopAndDestroyServer();

chrome/browser/net/predictor_browsertest.cc

@@ -30,6 +30,7 @@
 #include "chrome/browser/browsing_data/browsing_data_helper.h"
 #include "chrome/browser/browsing_data/chrome_browsing_data_remover_delegate.h"
 #include "chrome/browser/net/predictor.h"
+#include "chrome/browser/predictors/loading_predictor_config.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
@@ -514,7 +515,9 @@ class PredictorBrowserTest : public InProcessBrowserTest {
         Predictor::kMaxSpeculativeResolveQueueDelayMs + 300);
     rule_based_resolver_proc_->AddRuleWithLatency("delay.google.com",
                                                   "127.0.0.1", 1000 * 60);
-    scoped_feature_list_.InitAndEnableFeature(features::kPreconnectMore);
+    scoped_feature_list_.InitWithFeatures(
+        {features::kPreconnectMore},
+        {predictors::kSpeculativePreconnectFeature});
   }
 
   ~PredictorBrowserTest() override {}

testing/variations/fieldtrial_testing_config.json

@@ -3427,6 +3427,27 @@
             ]
         }
     ],
+    "SpeculativePreconnectValidation": [
+        {
+            "platforms": [
+                "win",
+                "mac",
+                "linux",
+                "android"
+            ],
+            "experiments": [
+                {
+                    "name": "Preconnect2",
+                    "params": {
+                        "mode": "preconnect"
+                    },
+                    "enable_features": [
+                        "SpeculativePreconnect"
+                    ]
+                }
+            ]
+        }
+    ],
     "StabilityDebugging": [
         {
             "platforms": [