[omnibox] get rid of test::ScopedFeatureList from on device head

provider unittest.

Its function base::FieldTrialList::BackupInstanceForTesting()
causes flakiness in chrome linux tsan test, e.g.
https://screenshot.googleplex.com/NF0rm8HZPhn
https://screenshot.googleplex.com/NvL2qn78tLk

I've put https://crrev.com/c/1888691 in patchset1 as a reference for
code review (in case the previous CL is reverted).

Change-Id: Ib34273087bc142df3efd122d13b08879f4b81a23
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1895869Reviewed-by: Tommy Li <tommycli@chromium.org>
Commit-Queue: Ce Chen <cch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712270}

components/omnibox/browser/on_device_head_provider.cc

@@ -98,7 +98,8 @@ OnDeviceHeadProvider::~OnDeviceHeadProvider() {
 }
 
 bool OnDeviceHeadProvider::IsOnDeviceHeadProviderAllowed(
-    const AutocompleteInput& input) {
+    const AutocompleteInput& input,
+    const std::string& incognito_serve_mode) {
   // Only accept asynchronous request.
   if (!input.want_asynchronous_matches() ||
       input.type() == metrics::OmniboxInputType::EMPTY)
@@ -114,12 +115,10 @@ bool OnDeviceHeadProvider::IsOnDeviceHeadProviderAllowed(
   //    request; this is the default behavior;
   // 2. incognito-only: only serve incognito request;
   // 3. always-serve: always serve regardless of incognito.
-  const std::string mode = base::GetFieldTrialParamValueByFeature(
-      omnibox::kOnDeviceHeadProvider, "IncognitoServeMode");
-  if (mode != "always-serve") {
-    if (client()->IsOffTheRecord() && mode != "incognito-only")
+  if (incognito_serve_mode != "always-serve") {
+    if (client()->IsOffTheRecord() && incognito_serve_mode != "incognito-only")
       return false;
-    if (!client()->IsOffTheRecord() && mode == "incognito-only")
+    if (!client()->IsOffTheRecord() && incognito_serve_mode == "incognito-only")
       return false;
   }
 
@@ -138,7 +137,9 @@ void OnDeviceHeadProvider::Start(const AutocompleteInput& input,
   // Cancel any in-progress request.
   Stop(!minimal_changes, false);
 
-  if (!IsOnDeviceHeadProviderAllowed(input)) {
+  const std::string mode = base::GetFieldTrialParamValueByFeature(
+      omnibox::kOnDeviceHeadProvider, "IncognitoServeMode");
+  if (!IsOnDeviceHeadProviderAllowed(input, mode)) {
     matches_.clear();
     return;
   }

components/omnibox/browser/on_device_head_provider.h

@@ -45,7 +45,8 @@ class OnDeviceHeadProvider : public AutocompleteProvider {
                        AutocompleteProviderListener* listener);
   ~OnDeviceHeadProvider() override;
 
-  bool IsOnDeviceHeadProviderAllowed(const AutocompleteInput& input);
+  bool IsOnDeviceHeadProviderAllowed(const AutocompleteInput& input,
+                                     const std::string& incognito_serve_mode);
 
   // Helper functions used for asynchronous search to the on device head model.
   // The Autocomplete input and output from the model will be passed from

components/omnibox/browser/on_device_head_provider_unittest.cc

@@ -8,7 +8,6 @@
 #include "base/path_service.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
-#include "base/test/scoped_feature_list.h"
 #include "base/test/task_environment.h"
 #include "build/build_config.h"
 #include "components/omnibox/browser/autocomplete_input.h"
@@ -16,7 +15,6 @@
 #include "components/omnibox/browser/fake_autocomplete_provider_client.h"
 #include "components/omnibox/browser/on_device_head_serving.h"
 #include "components/omnibox/browser/test_scheme_classifier.h"
-#include "components/omnibox/common/omnibox_features.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -65,8 +63,10 @@ class OnDeviceHeadProviderTest : public testing::Test,
     }
   }
 
-  bool IsOnDeviceHeadProviderAllowed(const AutocompleteInput& input) {
-    return provider_->IsOnDeviceHeadProviderAllowed(input);
+  bool IsOnDeviceHeadProviderAllowed(const AutocompleteInput& input,
+                                     const std::string& incognito_serve_mode) {
+    return provider_->IsOnDeviceHeadProviderAllowed(input,
+                                                    incognito_serve_mode);
   }
 
   base::test::TaskEnvironment task_environment_;
@@ -85,7 +85,7 @@ TEST_F(OnDeviceHeadProviderTest, ServingInstanceNotCreated) {
   EXPECT_CALL(*client_.get(), SearchSuggestEnabled())
       .WillRepeatedly(Return(true));
 
-  ASSERT_TRUE(IsOnDeviceHeadProviderAllowed(input));
+  ASSERT_TRUE(IsOnDeviceHeadProviderAllowed(input, ""));
 
   provider_->Start(input, false);
   if (!provider_->done())
@@ -101,7 +101,7 @@ TEST_F(OnDeviceHeadProviderTest, RejectSynchronousRequest) {
                           TestSchemeClassifier());
   input.set_want_asynchronous_matches(false);
 
-  ASSERT_FALSE(IsOnDeviceHeadProviderAllowed(input));
+  ASSERT_FALSE(IsOnDeviceHeadProviderAllowed(input, ""));
 }
 
 TEST_F(OnDeviceHeadProviderTest, TestIfIncognitoIsAllowed) {
@@ -115,25 +115,13 @@ TEST_F(OnDeviceHeadProviderTest, TestIfIncognitoIsAllowed) {
       .WillRepeatedly(Return(true));
 
   // By default incognito request will be rejected.
-  ASSERT_FALSE(IsOnDeviceHeadProviderAllowed(input));
+  ASSERT_FALSE(IsOnDeviceHeadProviderAllowed(input, ""));
 
   // Now enable for incognito only.
-  {
-    base::test::ScopedFeatureList feature_list;
-    feature_list.InitAndEnableFeatureWithParameters(
-        omnibox::kOnDeviceHeadProvider,
-        {{"IncognitoServeMode", "incognito-only"}});
-    ASSERT_TRUE(IsOnDeviceHeadProviderAllowed(input));
-  }
+  ASSERT_TRUE(IsOnDeviceHeadProviderAllowed(input, "incognito-only"));
 
   // Test "always-serve" mode.
-  {
-    base::test::ScopedFeatureList feature_list;
-    feature_list.InitAndEnableFeatureWithParameters(
-        omnibox::kOnDeviceHeadProvider,
-        {{"IncognitoServeMode", "always-serve"}});
-    ASSERT_TRUE(IsOnDeviceHeadProviderAllowed(input));
-  }
+  ASSERT_TRUE(IsOnDeviceHeadProviderAllowed(input, "always-serve"));
 }
 
 TEST_F(OnDeviceHeadProviderTest, RejectOnFocusRequest) {
@@ -146,7 +134,7 @@ TEST_F(OnDeviceHeadProviderTest, RejectOnFocusRequest) {
   EXPECT_CALL(*client_.get(), IsOffTheRecord()).WillRepeatedly(Return(false));
   EXPECT_CALL(*client_.get(), SearchSuggestEnabled()).WillOnce(Return(true));
 
-  ASSERT_FALSE(IsOnDeviceHeadProviderAllowed(input));
+  ASSERT_FALSE(IsOnDeviceHeadProviderAllowed(input, ""));
 }
 
 TEST_F(OnDeviceHeadProviderTest, NoMatches) {
@@ -159,7 +147,7 @@ TEST_F(OnDeviceHeadProviderTest, NoMatches) {
   EXPECT_CALL(*client_.get(), SearchSuggestEnabled())
       .WillRepeatedly(Return(true));
 
-  ASSERT_TRUE(IsOnDeviceHeadProviderAllowed(input));
+  ASSERT_TRUE(IsOnDeviceHeadProviderAllowed(input, ""));
 
   provider_->Start(input, false);
   if (!provider_->done())
@@ -179,7 +167,7 @@ TEST_F(OnDeviceHeadProviderTest, HasMatches) {
   EXPECT_CALL(*client_.get(), SearchSuggestEnabled())
       .WillRepeatedly(Return(true));
 
-  ASSERT_TRUE(IsOnDeviceHeadProviderAllowed(input));
+  ASSERT_TRUE(IsOnDeviceHeadProviderAllowed(input, ""));
 
   provider_->Start(input, false);
   if (!provider_->done())
@@ -206,8 +194,8 @@ TEST_F(OnDeviceHeadProviderTest, CancelInProgressRequest) {
   EXPECT_CALL(*client_.get(), SearchSuggestEnabled())
       .WillRepeatedly(Return(true));
 
-  ASSERT_TRUE(IsOnDeviceHeadProviderAllowed(input1));
-  ASSERT_TRUE(IsOnDeviceHeadProviderAllowed(input2));
+  ASSERT_TRUE(IsOnDeviceHeadProviderAllowed(input1, ""));
+  ASSERT_TRUE(IsOnDeviceHeadProviderAllowed(input2, ""));
 
   provider_->Start(input1, false);
   EXPECT_FALSE(provider_->done());