Previews - Only construct Previews Opt Guide for DataSaver Users.

This adds an additional check to prevent non-DataSaver users from
registering optimization types with the the Optimziation Guide
even though they would not be used within Previews code.


Bug: 1042429
Change-Id: Ibf6073aafcdde35939122f0b043b0c5b53b573bc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2097558
Commit-Queue: Michael Crouse <mcrouse@chromium.org>
Reviewed-by: Sophie Chang <sophiechang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#749224}

chrome/browser/optimization_guide/optimization_guide_keyed_service_browsertest.cc

@@ -197,7 +197,7 @@ class OptimizationGuideKeyedServiceBrowserTest
     OptimizationGuideKeyedServiceFactory::GetForProfile(browser()->profile())
         ->RegisterOptimizationTypesAndTargets(
             {optimization_guide::proto::NOSCRIPT},
-            /*optimization_targets=*/{});
+            {optimization_guide::proto::OPTIMIZATION_TARGET_PAINFUL_PAGE_LOAD});
 
     // Set up an OptimizationGuideKeyedService consumer.
     consumer_.reset(new OptimizationGuideConsumerWebContentsObserver(

chrome/browser/optimization_guide/prediction/prediction_manager_browsertest.cc

@@ -255,6 +255,7 @@ class PredictionManagerBrowserTest : public InProcessBrowserTest {
   }
 
   void SetUpCommandLine(base::CommandLine* cmd) override {
+    cmd->AppendSwitch("enable-spdy-proxy-auth");
     cmd->AppendSwitch(optimization_guide::switches::
                           kFetchModelsAndHostModelFeaturesOverrideTimer);
 

chrome/browser/previews/previews_browsertest.cc

@@ -439,3 +439,34 @@ IN_PROC_BROWSER_TEST_P(PreviewsNoScriptBrowserTest,
     EXPECT_FALSE(noscript_css_requested());
   }
 }
+
+// This test class disables DataSaver.
+class PreviewsDataSaverDisabledBrowserTest
+    : public PreviewsNoScriptBrowserTest {
+ public:
+  PreviewsDataSaverDisabledBrowserTest() = default;
+
+  ~PreviewsDataSaverDisabledBrowserTest() override = default;
+
+  void SetUpCommandLine(base::CommandLine* cmd) override {
+    PreviewsNoScriptBrowserTest::SetUpCommandLine(cmd);
+    cmd->RemoveSwitch("enable-spdy-proxy-auth");
+  }
+};
+
+INSTANTIATE_TEST_SUITE_P(ShouldDisablePreview,
+                         PreviewsDataSaverDisabledBrowserTest,
+                         ::testing::Bool());
+
+IN_PROC_BROWSER_TEST_P(PreviewsDataSaverDisabledBrowserTest,
+                       NoPreviewWithDataSaverDisabled) {
+  base::HistogramTester histogram_tester;
+  ui_test_utils::NavigateToURL(browser(), https_url());
+
+  // Verify loaded noscript tag triggered js file and not css file.
+  EXPECT_TRUE(noscript_js_requested());
+  EXPECT_FALSE(noscript_css_requested());
+
+  histogram_tester.ExpectTotalCount("OptimizationGuide.ApplyDecision.NoScript",
+                                    0);
+}

chrome/browser/previews/previews_service.cc

@@ -21,6 +21,7 @@
 #include "chrome/common/chrome_constants.h"
 #include "components/blacklist/opt_out_blacklist/opt_out_store.h"
 #include "components/blacklist/opt_out_blacklist/sql/opt_out_store_sql.h"
+#include "components/data_reduction_proxy/core/browser/data_reduction_proxy_settings.h"
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_features.h"
 #include "components/data_reduction_proxy/core/common/data_reduction_proxy_params.h"
 #include "components/previews/content/previews_decider_impl.h"
@@ -197,7 +198,10 @@ void PreviewsService::Initialize(
   std::unique_ptr<previews::PreviewsOptimizationGuide> previews_opt_guide;
   OptimizationGuideKeyedService* optimization_guide_keyed_service =
       OptimizationGuideKeyedServiceFactory::GetForProfile(profile);
-  if (optimization_guide_keyed_service) {
+  if (optimization_guide_keyed_service &&
+      data_reduction_proxy::DataReductionProxySettings::
+          IsDataSaverEnabledByUser(profile->IsOffTheRecord(),
+                                   profile->GetPrefs())) {
     previews_opt_guide = std::make_unique<previews::PreviewsOptimizationGuide>(
         optimization_guide_keyed_service);
   }