[Android] Simplify "network predictions" preference to a boolean value.

chrome/browser/prefetch/prefetch_browsertest.cc

Index: chrome/browser/prefetch/prefetch_browsertest.cc
diff --git a/chrome/browser/prefetch/prefetch_browsertest.cc b/chrome/browser/prefetch/prefetch_browsertest.cc
index fcf79080fc19f2a6335c68ff1467f10b0daf91ad..41878f1182c5318de93346386d29189bc2561ce0 100644
--- a/chrome/browser/prefetch/prefetch_browsertest.cc
+++ b/chrome/browser/prefetch/prefetch_browsertest.cc
@@ -92,8 +92,8 @@ class PrefetchBrowserTestPredictionDisabled : public PrefetchBrowserTestBase {
 IN_PROC_BROWSER_TEST_F(PrefetchBrowserTestPredictionDisabled,
                        ExperimentDisabled) {
   EXPECT_TRUE(RunPrefetchExperiment(false, browser()));
-  // Should not prefetch even if preference is ALWAYS.
-  SetPreference(NetworkPredictionOptions::NETWORK_PREDICTION_ALWAYS);
+  // Should not prefetch even if preference is WIFI_ONLY.
+  SetPreference(NetworkPredictionOptions::NETWORK_PREDICTION_WIFI_ONLY);
   EXPECT_TRUE(RunPrefetchExperiment(false, browser()));
 }
 
@@ -113,17 +113,6 @@ IN_PROC_BROWSER_TEST_F(PrefetchBrowserTestPrediction, PreferenceWorks) {
     EXPECT_TRUE(RunPrefetchExperiment(false, browser()));
   }
 
-  // Set preference to ALWAYS: always prefetch.

[newt (away), 2016/02/22 19:45:38]

The "ALWAYS" state is being merged into the WIFI_ONLY state. Right now, their
behavior is identical. In a future CL, the states will actually be merged.

-  SetPreference(NetworkPredictionOptions::NETWORK_PREDICTION_ALWAYS);
-  {
-    scoped_ptr<NetworkChangeNotifier> mock(new MockNetworkChangeNotifierWIFI);
-    EXPECT_TRUE(RunPrefetchExperiment(true, browser()));
-  }
-  {
-    scoped_ptr<NetworkChangeNotifier> mock(new MockNetworkChangeNotifier4G);
-    EXPECT_TRUE(RunPrefetchExperiment(true, browser()));
-  }
-
   // Set preference to NEVER: never prefetch.
   SetPreference(NetworkPredictionOptions::NETWORK_PREDICTION_NEVER);
   {