Request location perm. on enabling Physical Web

If we do not already have the location permission, we need to request
it when the user enables the Physical Web feature in the privacy
settings.

BUG=529962

Review URL: https://codereview.chromium.org/1535883002

Cr-Commit-Position: refs/heads/master@{#367028}

chrome/android/java/src/org/chromium/chrome/browser/preferences/privacy/PhysicalWebPreferenceFragment.java

@@ -4,11 +4,15 @@
 
 package org.chromium.chrome.browser.preferences.privacy;
 
+import android.Manifest;
+import android.content.pm.PackageManager;
+import android.os.Build;
 import android.os.Bundle;
 import android.preference.Preference;
 import android.preference.Preference.OnPreferenceChangeListener;
 import android.preference.PreferenceFragment;
 
+import org.chromium.base.Log;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.preferences.ChromeSwitchPreference;
 
@@ -16,8 +20,9 @@ import org.chromium.chrome.browser.preferences.ChromeSwitchPreference;
  * Fragment to manage the Physical Web preference and to explain to the user what it does.
  */
 public class PhysicalWebPreferenceFragment extends PreferenceFragment {
-
+    private static final String TAG = "PhysicalWeb";
     private static final String PREF_PHYSICAL_WEB_SWITCH = "physical_web_switch";
+    private static final int REQUEST_ID = 0;
 
     @Override
     public void onCreate(Bundle savedInstanceState) {
@@ -27,6 +32,46 @@ public class PhysicalWebPreferenceFragment extends PreferenceFragment {
         initPhysicalWebSwitch();
     }
 
+    private void ensureLocationPermission() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+            if (getActivity().checkSelfPermission(Manifest.permission.ACCESS_FINE_LOCATION)
+                    == PackageManager.PERMISSION_GRANTED) {
+                Log.d(TAG, "Location permission already granted");
+                setPhysicalWebEnabled(true);
+                return;
+            }
+
+            Log.d(TAG, "Requesting location permission");
+            requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_ID);
+            return;
+        }
+
+        setPhysicalWebEnabled(true);
+    }
+
+
+    @Override
+    public void onRequestPermissionsResult(int requestCode, String permissions[],
+                                           int[] grantResults) {
+        // TODO(cco3): Add UMA here.
+        switch (requestCode) {
+            case REQUEST_ID:
+                if (grantResults.length > 0
+                        && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+                    Log.d(TAG, "Location permission granted");
+                } else {
+                    Log.d(TAG, "Location permission rejected");
+                }
+                break;
+            default:
+        }
+
+        // It doesn't matter whether we were given the location permission or not.  We will flip
+        // the setting to true and let the PreferenceManager figure out what to do with the
+        // location permission or lack thereof.
+        setPhysicalWebEnabled(true);
+    }
+
     private void initPhysicalWebSwitch() {
         ChromeSwitchPreference physicalWebSwitch =
                 (ChromeSwitchPreference) findPreference(PREF_PHYSICAL_WEB_SWITCH);
@@ -38,11 +83,17 @@ public class PhysicalWebPreferenceFragment extends PreferenceFragment {
         physicalWebSwitch.setOnPreferenceChangeListener(new OnPreferenceChangeListener() {
             @Override
             public boolean onPreferenceChange(Preference preference, Object newValue) {
-                PrivacyPreferencesManager.getInstance(getActivity()).setPhysicalWebEnabled(
-                        (boolean) newValue);
+                if ((boolean) newValue) {
+                    ensureLocationPermission();
+                } else {
+                    setPhysicalWebEnabled(false);
+                }
                 return true;
             }
         });
     }
 
-}
\ No newline at end of file
+    private void setPhysicalWebEnabled(boolean value) {
+        PrivacyPreferencesManager.getInstance(getActivity()).setPhysicalWebEnabled(value);
+    }
+}