If location services are turned off, have the BT chooser prompt the user to turn them on.

chrome/android/java/src/org/chromium/chrome/browser/BluetoothChooserDialog.java

Index: chrome/android/java/src/org/chromium/chrome/browser/BluetoothChooserDialog.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/BluetoothChooserDialog.java b/chrome/android/java/src/org/chromium/chrome/browser/BluetoothChooserDialog.java
index 3483a645626c69f58936686326bf4dde328c5443..834701f7f1fc0240ed24a1e765f86457adcea11d 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/BluetoothChooserDialog.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/BluetoothChooserDialog.java
@@ -6,9 +6,12 @@ package org.chromium.chrome.browser;
 
 import android.Manifest;
 import android.app.Activity;
+import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
-import android.content.pm.PackageManager;
+import android.content.IntentFilter;
+import android.location.LocationManager;
+import android.provider.Settings;
 import android.text.SpannableString;
 import android.text.TextUtils;
 import android.view.View;
@@ -17,6 +20,7 @@ import org.chromium.base.VisibleForTesting;
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.omnibox.OmniboxUrlEmphasizer;
+import org.chromium.chrome.browser.preferences.LocationSettings;
 import org.chromium.chrome.browser.profiles.Profile;
 import org.chromium.ui.base.WindowAndroid;
 import org.chromium.ui.text.NoUnderlineClickableSpan;
@@ -27,6 +31,8 @@ import org.chromium.ui.text.SpanApplier.SpanInfo;
  * A dialog for picking available Bluetooth devices. This dialog is shown when a website requests to
  * pair with a certain class of Bluetooth devices (e.g. through a bluetooth.requestDevice Javascript
  * call).
+ *
+ * The dialog is shown by create() or show(), and always runs finishDialog() as it's closing.
  */
 public class BluetoothChooserDialog
         implements ItemChooserDialog.ItemSelectedCallback, WindowAndroid.PermissionCallback {
@@ -67,6 +73,7 @@ public class BluetoothChooserDialog
         ADAPTER_OFF,
         ADAPTER_OFF_HELP,
         REQUEST_LOCATION_PERMISSION,
+        REQUEST_LOCATION_SERVICES,
         NEED_LOCATION_PERMISSION_HELP,
         RESTART_SEARCH,
     }
@@ -129,30 +136,35 @@ public class BluetoothChooserDialog
                 new ItemChooserDialog.ItemChooserLabels(title, searching, noneFound,
                         statusIdleNoneFound, statusIdleSomeFound, positiveButton);
         mItemChooserDialog = new ItemChooserDialog(mActivity, this, labels);
+
+        mActivity.registerReceiver(mLocationModeBroadcastReceiver,
+                new IntentFilter(LocationManager.MODE_CHANGED_ACTION));
+    }
+
+    // Called to report the dialog's results back to native code.
+    private void finishDialog(int resultCode, String id) {
+        mActivity.unregisterReceiver(mLocationModeBroadcastReceiver);
+        if (mNativeBluetoothChooserDialogPtr != 0) {
+            nativeOnDialogFinished(mNativeBluetoothChooserDialogPtr, resultCode, id);
+        }
     }
 
     @Override
     public void onItemSelected(String id) {
-        if (mNativeBluetoothChooserDialogPtr != 0) {
-            if (id.isEmpty()) {
-                nativeOnDialogFinished(
-                        mNativeBluetoothChooserDialogPtr, DIALOG_FINISHED_CANCELLED, "");
-            } else {
-                nativeOnDialogFinished(
-                        mNativeBluetoothChooserDialogPtr, DIALOG_FINISHED_SELECTED, id);
-            }
+        if (id.isEmpty()) {
+            finishDialog(DIALOG_FINISHED_CANCELLED, "");
+        } else {
+            finishDialog(DIALOG_FINISHED_SELECTED, id);
         }
     }
 
     @Override
     public void onRequestPermissionsResult(String[] permissions, int[] grantResults) {
-        for (int i = 0; i < grantResults.length; i++) {
+        for (int i = 0; i < permissions.length; i++) {
             if (permissions[i].equals(Manifest.permission.ACCESS_COARSE_LOCATION)) {
-                if (grantResults[i] == PackageManager.PERMISSION_GRANTED) {
+                if (checkLocationServicesAndPermission()) {
                     mItemChooserDialog.clear();
                     nativeRestartSearch(mNativeBluetoothChooserDialogPtr);
-                } else {
-                    checkLocationPermission();
                 }
                 return;
             }
@@ -160,25 +172,63 @@ public class BluetoothChooserDialog
         // If the location permission is not present, leave the currently-shown message in place.
     }
 
-    private void checkLocationPermission() {
-        if (mWindowAndroid.hasPermission(Manifest.permission.ACCESS_COARSE_LOCATION)
-                || mWindowAndroid.hasPermission(Manifest.permission.ACCESS_FINE_LOCATION)) {
-            return;
-        }
-
-        if (!mWindowAndroid.canRequestPermission(Manifest.permission.ACCESS_COARSE_LOCATION)) {
-            if (mNativeBluetoothChooserDialogPtr != 0) {
-                nativeOnDialogFinished(
-                        mNativeBluetoothChooserDialogPtr, DIALOG_FINISHED_DENIED_PERMISSION, "");
-                return;
+    @VisibleForTesting
+    final BroadcastReceiver mLocationModeBroadcastReceiver = new BroadcastReceiver() {
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            if (LocationManager.MODE_CHANGED_ACTION.equals(intent.getAction())) {
+                if (checkLocationServicesAndPermission()) {
+                    mItemChooserDialog.clear();
+                    nativeRestartSearch(mNativeBluetoothChooserDialogPtr);
+                }
             }
         }
+    };
 
-        SpannableString needLocationMessage = SpanApplier.applySpans(
-                mActivity.getString(R.string.bluetooth_need_location_permission),
-                new SpanInfo("<link>", "</link>",
-                        new BluetoothClickableSpan(
-                                     LinkType.REQUEST_LOCATION_PERMISSION, mActivity)));
+    // Returns true if Location Services is on and Chrome has permission to see the user's location.
+    private boolean checkLocationServicesAndPermission() {
+        final boolean havePermission =
+                mWindowAndroid.hasPermission(Manifest.permission.ACCESS_COARSE_LOCATION)
+                || mWindowAndroid.hasPermission(Manifest.permission.ACCESS_FINE_LOCATION);
+        final boolean locationServicesOn =
+                LocationSettings.getInstance().isSystemLocationSettingEnabled();

[Jeffrey Yasskin, 2016/06/03 01:52:48]

It's a little odd for this chooser to call into preferences.LocationSettings.
Would folks be happy to see me refactor that class into a more general location,
since the concept is used ~6 places in the codebase after this change? If so,
where would you like it? Is it a base/ kind of utility?

[Finnur, 2016/06/03 02:25:04]

These questions are probably more appropriate for Ted. I don't have a strong
opinion, but don't mind seeing this be made more general.

[Ted C, 2016/06/07 00:30:14]

It seems to only be used in preferences right now.  I think it's fine to move it
up somewhere out of preferences, but I'm not sure how much we need to move it to
base.

In particular, we have an internal version of the class and moving it to base
will make that more difficult.

The internal one is under org.chromium.chrome.browser.location so we could
conceivably move it there easier.

+
+        if (!havePermission
+                && !mWindowAndroid.canRequestPermission(
+                           Manifest.permission.ACCESS_COARSE_LOCATION)) {
+            // Immediately close the dialog because the user has asked Chrome not to request the
+            // location permission.
+            finishDialog(DIALOG_FINISHED_DENIED_PERMISSION, "");
+            return false;
+        }
+
+        // Compute the message to show the user.
+        final SpanInfo permissionSpan = new SpanInfo("<permission_link>", "</permission_link>",
+                new BluetoothClickableSpan(LinkType.REQUEST_LOCATION_PERMISSION, mActivity));
+        final SpanInfo servicesSpan = new SpanInfo("<services_link>", "</services_link>",
+                new BluetoothClickableSpan(LinkType.REQUEST_LOCATION_SERVICES, mActivity));
+        final SpannableString needLocationMessage;
+        if (havePermission) {
+            if (locationServicesOn) {
+                // We don't need to request anything.
+                return true;
+            } else {
+                needLocationMessage = SpanApplier.applySpans(
+                        mActivity.getString(R.string.bluetooth_need_location_services_on),
+                        servicesSpan);
+            }
+        } else {
+            if (locationServicesOn) {
+                needLocationMessage = SpanApplier.applySpans(
+                        mActivity.getString(R.string.bluetooth_need_location_permission),
+                        permissionSpan);
+            } else {
+                needLocationMessage = SpanApplier.applySpans(
+                        mActivity.getString(
+                                R.string.bluetooth_need_location_permission_and_services_on),
+                        permissionSpan, servicesSpan);
+            }
+        }
 
         SpannableString needLocationStatus = SpanApplier.applySpans(
                 mActivity.getString(R.string.bluetooth_need_location_permission_help),
@@ -187,6 +237,7 @@ public class BluetoothChooserDialog
                                      LinkType.NEED_LOCATION_PERMISSION_HELP, mActivity)));
 
         mItemChooserDialog.setErrorState(needLocationMessage, needLocationStatus);
+        return false;
     }
 
     private class BluetoothClickableSpan extends NoUnderlineClickableSpan {
@@ -217,9 +268,8 @@ public class BluetoothChooserDialog
                     break;
                 }
                 case ADAPTER_OFF: {
-                    Intent intent = new Intent();
-                    intent.setAction(android.provider.Settings.ACTION_BLUETOOTH_SETTINGS);
-                    mContext.startActivity(intent);
+                    mContext.startActivity(
+                            new Intent(android.provider.Settings.ACTION_BLUETOOTH_SETTINGS));
                     break;
                 }
                 case ADAPTER_OFF_HELP: {
@@ -233,6 +283,10 @@ public class BluetoothChooserDialog
                             BluetoothChooserDialog.this);
                     break;
                 }
+                case REQUEST_LOCATION_SERVICES: {
+                    mContext.startActivity(new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS));
+                    break;
+                }
                 case NEED_LOCATION_PERMISSION_HELP: {
                     nativeShowNeedLocationPermissionLink(mNativeBluetoothChooserDialogPtr);
                     closeDialog();
@@ -317,9 +371,10 @@ public class BluetoothChooserDialog
     void notifyDiscoveryState(int discoveryState) {
         switch (discoveryState) {
             case DISCOVERY_FAILED_TO_START: {
-                // FAILED_TO_START might be caused by a missing Location permission.
+                // FAILED_TO_START might be caused by a missing Location
+                // permission or by the Location service being turned off.
                 // Check, and show a request if so.
-                checkLocationPermission();
+                checkLocationServicesAndPermission();
                 break;
             }
             case DISCOVERY_IDLE: {