Add the Play Store app search to the launcher.

components/arc/common/app.mojom

 // Copyright 2015 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.
 //
 // Next MinVersion: 20
 
 module arc.mojom;
 
 import "scale_factor.mojom";
 import "screen_rect.mojom";
+import "app_discovery_result.mojom";
 
 // Describes OrientationLock request.
 // Note: ChromeOS currently assumes the internal panel is always landscape.
 // All rotation angles mentioned here are measured clockwise.
 [Extensible]
 enum OrientationLock {
   NONE = 0,
   // Rotated 90 or 270 deg.
   PORTRAIT = 1,
   // Rotated 0 or 180 deg.
@@ skipping 205 matching lines @@
   [MinVersion=10] ShowPackageInfoOnPage@15(string package_name,
                                            ShowPackageInfoPage page,
                                            ScreenRect dimension_on_screen);
 
   // Sets notification setting for the package.
   [MinVersion=6] SetNotificationsEnabled@10(string package_name, bool enabled);
 
   // Sends a request to ARC to uninstall the given package.  Error (if ever
   // happens) is ignored, and uninstall option should appear in the UI.
   [MinVersion=2] UninstallPackage@5(string package_name);
+
+  // Starts a query for Playstore apps.

[Luis Héctor Chávez, 2017/06/15 15:37:25]

nit: Play Store.

[Jiaquan He, 2017/06/15 19:23:30]

Done.

+  [MinVersion=18] GetRecentAndSuggestedApps@16(

[Luis Héctor Chávez, 2017/06/15 15:37:25]

I think it's better to explicitly mention that this comes from play store in the
method name:

GetRecentAndSuggestedAppsFromPlayStore.

[Jiaquan He, 2017/06/15 19:23:31]

Done.

+      string query, int32 max_results) =>
+          (array<AppDiscoveryResult> results);
 };