Add a section to Site Settings listing USB devices.

chrome/android/java/src/org/chromium/chrome/browser/preferences/website/UsbChooserPreferences.java

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.preferences.website;
+
+import android.os.Bundle;
+import android.preference.Preference;
+import android.preference.PreferenceFragment;
+import android.support.v4.view.MenuItemCompat;
+import android.support.v7.widget.SearchView;
+import android.view.Menu;
+import android.view.MenuInflater;
+import android.view.MenuItem;
+import android.view.inputmethod.EditorInfo;
+import android.widget.ListView;
+import android.widget.TextView;
+
+import org.chromium.chrome.R;
+import org.chromium.chrome.browser.help.HelpAndFeedback;
+import org.chromium.chrome.browser.profiles.Profile;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Shows a list of USB devices that the user has granted websites permission to access.
+ *
+ * When the user selects an item UsbDevicePreferences is launched to show which sites have access
+ * to the device.
+ */
+public class UsbChooserPreferences
+        extends PreferenceFragment implements Preference.OnPreferenceClickListener {
+    // The site settings category we are showing.
+    private SiteSettingsCategory mCategory;
+    // Multiple sites may have access to the same device. A canonical UsbInfo for each device is
+    // therefore arbitrarily chosen to represent it. |mPermissionsByObject| lists all of the
+    // individual permission grants for that device. |mSitesByObject| lists all of the sites with
+    // access to that device.
+    //
+    // UsbInfo's hashCode() and equals() methods compare only the device it represents, not the
+    // origin to which permission was granted.
+    private Map<UsbInfo, LinkedList<UsbInfo>> mPermissionsByObject = new HashMap<>();

[Ted C, 2016/08/15 20:31:59]

unless you need some property of LinkedList, it'd be better to do Map<UsbInfo,
List<UsbInfo>> 

[Reilly Grant (use Gerrit), 2016/08/16 17:41:59]

It needs to be LinkedList so that it's Serializable.

[Ted C, 2016/08/17 14:49:13]

I guess the fundamental question I have is why LinkedList vs ArrayList?

We use ArrayList much more commonly.  That is also the basis for my Iterator
vs i++ comment in the other file.  An ArrayList is not penalized for
lookups in the list while LinkedList is.  Personally, I'd vote for switching
to ArrayList for nothing but consistency.

[Reilly Grant (use Gerrit), 2016/08/17 20:04:22]

Done.

+    private Map<UsbInfo, LinkedList<Website>> mSitesByObject = new HashMap<>();
+    // The view to show when the list is empty.
+    private TextView mEmptyView;
+    // The view for searching the list of items.
+    private SearchView mSearchView;
+    // If not blank, represents a substring to use to search for site names.
+    private String mSearch = "";
+
+    @Override
+    public void onActivityCreated(Bundle savedInstanceState) {
+        addPreferencesFromResource(R.xml.single_chooser_preferences);
+        ListView listView = (ListView) getView().findViewById(android.R.id.list);
+        mEmptyView = (TextView) getView().findViewById(android.R.id.empty);
+        listView.setEmptyView(mEmptyView);
+        listView.setDivider(null);
+
+        String category = getArguments().getString(SingleCategoryPreferences.EXTRA_CATEGORY);
+        mCategory = SiteSettingsCategory.fromString(category);
+        String title = getArguments().getString(SingleCategoryPreferences.EXTRA_TITLE);
+        getActivity().setTitle(title);
+
+        setHasOptionsMenu(true);
+
+        super.onActivityCreated(savedInstanceState);
+    }
+
+    @Override
+    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
+        menu.clear();
+        inflater.inflate(R.menu.website_preferences_menu, menu);
+
+        MenuItem searchItem = menu.findItem(R.id.search);
+        mSearchView = (SearchView) MenuItemCompat.getActionView(searchItem);
+        mSearchView.setImeOptions(EditorInfo.IME_FLAG_NO_FULLSCREEN);
+        SearchView.OnQueryTextListener queryTextListener = new SearchView.OnQueryTextListener() {
+            @Override
+            public boolean onQueryTextSubmit(String query) {
+                return true;
+            }
+
+            @Override
+            public boolean onQueryTextChange(String query) {
+                // Make search case-insensitive.
+                query = query.toLowerCase();
+
+                if (query.equals(mSearch)) return true;
+
+                mSearch = query;
+                getInfo();
+                return true;
+            }
+        };
+        mSearchView.setOnQueryTextListener(queryTextListener);
+
+        MenuItem help =
+                menu.add(Menu.NONE, R.id.menu_id_targeted_help, Menu.NONE, R.string.menu_help);
+        help.setIcon(R.drawable.ic_help_and_feedback);
+    }
+
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        if (item.getItemId() == R.id.menu_id_targeted_help) {
+            HelpAndFeedback.getInstance(getActivity())
+                    .show(getActivity(), getString(R.string.help_context_settings),
+                            Profile.getLastUsedProfile(), null);
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    public void onResume() {
+        super.onResume();
+
+        getInfo();
+    }
+
+    private class ResultsPopulator implements WebsitePermissionsFetcher.WebsitePermissionsCallback {
+        @Override
+        public void onWebsitePermissionsAvailable(Collection<Website> sites) {
+            // This method may be called after the activity has been destroyed.
+            // In that case, bail out.
+            if (getActivity() == null) return;
+
+            mPermissionsByObject.clear();
+            mSitesByObject.clear();
+            for (Website site : sites) {
+                for (UsbInfo info : site.getUsbInfo()) {
+                    if (mSearch.isEmpty() || info.getName().toLowerCase().contains(mSearch)) {
+                        LinkedList<UsbInfo> permissionSet = mPermissionsByObject.get(info);

[Ted C, 2016/08/15 20:31:59]

naming nit, but it's odd to have these be called permissionSet when it's
actually a list.  permissionList and sitesList below make more sense to me.  

[Reilly Grant (use Gerrit), 2016/08/16 17:41:59]

Agreed, it was a HashSet in an earlier version of this patch.

+                        if (permissionSet == null) {
+                            permissionSet = new LinkedList<>();
+                            mPermissionsByObject.put(info, permissionSet);
+                        }
+                        permissionSet.add(info);
+                        LinkedList<Website> sitesSet = mSitesByObject.get(info);
+                        if (sitesSet == null) {
+                            sitesSet = new LinkedList<>();
+                            mSitesByObject.put(info, sitesSet);
+                        }
+                        sitesSet.add(site);
+                    }
+                }
+            }
+
+            resetList();
+        }
+    }
+
+    /**
+     * Refreshes |mPermissionsByObject| and |mSitesByObject| with new data from native.
+     *
+     * resetList() is called to refresh the view when the data is ready.
+     */
+    private void getInfo() {
+        WebsitePermissionsFetcher fetcher = new WebsitePermissionsFetcher(new ResultsPopulator());
+        fetcher.fetchPreferencesForCategory(mCategory);
+    }
+
+    private void resetList() {
+        getPreferenceScreen().removeAll();
+        addPreferencesFromResource(R.xml.single_chooser_preferences);
+
+        if (mPermissionsByObject.isEmpty() && mSearch.isEmpty() && mEmptyView != null) {
+            mEmptyView.setText(R.string.website_settings_usb_no_devices);
+        }
+
+        for (Map.Entry<UsbInfo, LinkedList<UsbInfo>> entry : mPermissionsByObject.entrySet()) {
+            Preference preference = new Preference(getActivity());
+            preference.getExtras().putSerializable(
+                    UsbDevicePreferences.EXTRA_USB_INFOS, entry.getValue());
+            preference.setIcon(R.drawable.settings_usb);
+            preference.setOnPreferenceClickListener(this);
+            preference.setTitle(entry.getKey().getName());
+            getPreferenceScreen().addPreference(preference);
+        }
+    }
+
+    @Override
+    public boolean onPreferenceClick(Preference preference) {
+        Bundle extras = preference.getExtras();
+        @SuppressWarnings("unchecked")
+        List<UsbInfo> info =
+                (List<UsbInfo>) extras.getSerializable(UsbDevicePreferences.EXTRA_USB_INFOS);
+        extras.putString(

[Ted C, 2016/08/15 20:31:59]

any reason we don't set these extras when we are building it in resetList above?
 Will they change between resetList and the time onPreferenceClick is called? 
Seems kinda odd to have it set it in both places.

[Reilly Grant (use Gerrit), 2016/08/16 17:41:59]

To avoid serializing a bunch of stuff that won't be necessary unless the entry
is actually tapped.

[Ted C, 2016/08/17 14:49:13]

Does it actually get serialized though?  Just adding extras doesn't do anything:
https://android.googlesource.com/platform/frameworks/base/+/master/core/java/...

It wouldn't happen unless the extra is being serialized when you are calling
addPreference above.
https://android.googlesource.com/platform/frameworks/base/+/master/core/java/...

Nothing obviously jumps out as forcing a serialization in the addPreference
call:
https://android.googlesource.com/platform/frameworks/base/+/master/core/java/...

I guess this just feels like a bit of premature optimization.

[Reilly Grant (use Gerrit), 2016/08/17 20:04:22]

Done.

+                SingleCategoryPreferences.EXTRA_TITLE, getActivity().getTitle().toString());
+        extras.putInt(UsbDevicePreferences.EXTRA_CATEGORY, mCategory.toContentSettingsType());
+        extras.putSerializable(
+                UsbDevicePreferences.EXTRA_SITES, mSitesByObject.get(info.get(0)));
+        preference.setFragment(
+                "org.chromium.chrome.browser.preferences.website.UsbDevicePreferences");

[Ted C, 2016/08/15 20:31:59]

can we use UsbDevicePreferences.class.getFullName() or something here...i always
forget in java which one should return this.

[Reilly Grant (use Gerrit), 2016/08/16 17:41:59]

Done.

+        return false;
+    }
+}