[CrOS Tether] Add chromeos switch for ignoring wired connections

This adds a chromeos switch to allow tether host scans to occur in
spite of ethernet connections. This is a followup to CL 1332693.

-----

TESTING:

I confirmed manually that turning off the switch prevented a host scan
when ethernet is plugged in while turning it on allowed the 'tether
host found' notification.


Bug: 904609
Change-Id: If0938796841228415c72fb6ccc9b0a52c3d64786
Reviewed-on: https://chromium-review.googlesource.com/c/1334206
Commit-Queue: Jordy Greenblatt <jordynass@chromium.org>
Reviewed-by: Jeremy Klein <jlklein@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607878}

chromeos/chromeos_switches.cc

@@ -558,6 +558,13 @@ const char kTestEncryptionMigrationUI[] = "test-encryption-migration-ui";
 // of fake networks desired, e.g. 'tether-stub=2'.
 const char kTetherStub[] = "tether-stub";
 
+// Tells the Chromebook to scan for a tethering host even if there is already a
+// wired connection. This allows end-to-end tests to be deployed over ethernet
+// without that connection preventing scans and thereby blocking the testing of
+// cases with no preexisting connection. Should be used only for testing.
+const char kTetherHostScansIgnoreWiredConnections[] =
+    "tether-host-scans-ignore-wired-connecitons";
+
 // List of locales supported by voice interaction.
 const char kVoiceInteractionLocales[] = "voice-interaction-supported-locales";
 
@@ -703,6 +710,11 @@ bool IsInstantTetheringBackgroundAdvertisingSupported() {
       kInstantTetheringBackgroundAdvertisementSupport);
 }
 
+bool ShouldTetherHostScansIgnoreWiredConnections() {
+  return base::CommandLine::ForCurrentProcess()->HasSwitch(
+      kTetherHostScansIgnoreWiredConnections);
+}
+
 bool ShouldShowPlayStoreInDemoMode() {
   return base::CommandLine::ForCurrentProcess()->HasSwitch(kShowPlayInDemoMode);
 }

chromeos/chromeos_switches.h

@@ -155,6 +155,7 @@ CHROMEOS_EXPORT extern const char kShowPlayInDemoMode[];
 CHROMEOS_EXPORT extern const char kStubCrosSettings[];
 CHROMEOS_EXPORT extern const char kTestEncryptionMigrationUI[];
 CHROMEOS_EXPORT extern const char kTetherStub[];
+CHROMEOS_EXPORT extern const char kTetherHostScansIgnoreWiredConnections[];
 CHROMEOS_EXPORT extern const char kVoiceInteractionLocales[];
 CHROMEOS_EXPORT extern const char kWaitForInitialPolicyFetchForTest[];
 CHROMEOS_EXPORT extern const char kWakeOnWifiPacket[];
@@ -216,9 +217,14 @@ CHROMEOS_EXPORT bool ShouldHideActiveAppsFromShelf();
 CHROMEOS_EXPORT bool ShouldShowShelfHoverPreviews();
 
 // Returns true if Instant Tethering should support hosts which use the
-// background advertisement model
+// background advertisement model.
 CHROMEOS_EXPORT bool IsInstantTetheringBackgroundAdvertisingSupported();
 
+// Returns true if the Chromebook should ignore its wired connections when
+// deciding whether to run scans for tethering hosts. Should be used only for
+// testing.
+CHROMEOS_EXPORT bool ShouldTetherHostScansIgnoreWiredConnections();
+
 // Returns true if Play Store should be available in Demo Mode.
 // TODO(michaelpg): Remove after M71 branch to re-enable Play Store by default.
 CHROMEOS_EXPORT bool ShouldShowPlayStoreInDemoMode();

chromeos/components/tether/host_scan_scheduler_impl.cc

@@ -11,6 +11,7 @@
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/default_clock.h"
 #include "chromeos/chromeos_features.h"
+#include "chromeos/chromeos_switches.h"
 #include "chromeos/components/proximity_auth/logging/logging.h"
 #include "chromeos/network/network_handler.h"
 #include "chromeos/network/network_state.h"
@@ -54,7 +55,6 @@ HostScanSchedulerImpl::HostScanSchedulerImpl(
       host_scan_batch_timer_(std::make_unique<base::OneShotTimer>()),
       clock_(base::DefaultClock::GetInstance()),
       task_runner_(base::ThreadTaskRunnerHandle::Get()),
-      ignore_wired_networks_(false),
       is_screen_locked_(session_manager_->IsScreenLocked()),
       weak_ptr_factory_(this) {
   network_state_handler_->AddObserver(this, FROM_HERE);
@@ -84,7 +84,8 @@ HostScanSchedulerImpl::~HostScanSchedulerImpl() {
 
 void HostScanSchedulerImpl::AttemptScanIfOffline() {
   const chromeos::NetworkTypePattern network_type_pattern =
-      ignore_wired_networks_ ? chromeos::NetworkTypePattern::Wireless()
+      chromeos::switches::ShouldTetherHostScansIgnoreWiredConnections()
+          ? chromeos::NetworkTypePattern::Wireless()
           : chromeos::NetworkTypePattern::Default();
   const chromeos::NetworkState* first_network =
       network_state_handler_->FirstNetworkByType(network_type_pattern);

chromeos/components/tether/host_scan_scheduler_impl.h

@@ -84,11 +84,6 @@ class HostScanSchedulerImpl : public HostScanScheduler,
 
   base::Time last_scan_batch_start_timestamp_;
   base::Time last_scan_end_timestamp_;
-
-  // TODO(crbug.com/904609): Read ignore_wired_networks_ from flag defaulting to
-  // false. Scan for tethering hosts even if there is a wired connection to
-  // allow end-to-end tests to be deployed and run without unplugging ethernet.
-  bool ignore_wired_networks_;
   bool is_screen_locked_;
 
   base::WeakPtrFactory<HostScanSchedulerImpl> weak_ptr_factory_;

chromeos/components/tether/host_scanner_impl.cc

@@ -269,7 +269,8 @@ bool HostScannerImpl::IsPotentialHotspotNotificationShowing() {
 
 bool HostScannerImpl::CanAvailableHostNotificationBeShown() {
   const chromeos::NetworkTypePattern network_type_pattern =
-      ignore_wired_networks_ ? chromeos::NetworkTypePattern::Wireless()
+      chromeos::switches::ShouldTetherHostScansIgnoreWiredConnections()
+          ? chromeos::NetworkTypePattern::Wireless()
           : chromeos::NetworkTypePattern::Default();
   // Note: If a network is active (i.e., connecting or connected), it will be
   // returned at the front of the list, so using FirstNetworkByType() guarantees

chromeos/components/tether/host_scanner_impl.h

@@ -14,6 +14,7 @@
 #include "base/observer_list.h"
 #include "base/time/clock.h"
 #include "base/time/time.h"
+#include "chromeos/chromeos_switches.h"
 #include "chromeos/components/tether/host_scanner.h"
 #include "chromeos/components/tether/host_scanner_operation.h"
 #include "chromeos/components/tether/notification_presenter.h"
@@ -132,10 +133,6 @@ class HostScannerImpl : public HostScanner,
   ConnectionPreserver* connection_preserver_;
   base::Clock* clock_;
 
-  // TODO(crbug.com/904609): Read ignore_wired_networks_ from flag defaulting to
-  // false. Scan for tethering hosts even if there is a wired connection to
-  // allow end-to-end tests to be deployed and run without unplugging ethernet.
-  bool ignore_wired_networks_ = false;
   bool is_fetching_hosts_ = false;
   bool was_notification_showing_when_current_scan_started_ = false;
   bool was_notification_shown_in_current_scan_ = false;