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";
@@ skipping 142 matching lines @@
   // details of installation result.
   [MinVersion=16] OnInstallationFinished@15(
       [MinVersion=17] InstallationResult? result@1);
 
   // Notifies that an application shortcut needs to be deleted. Shortcut is
   // defined by its |intent_uri| and |package_name|.
   [MinVersion=18] OnUninstallShortcut@16(string package_name,
                                          string intent_uri);
 };
 
+// Next method ID: 1
+// The GetRecentAndSuggestedApps interface calls an Phonesky API that starts
+// asynchronous tasks and returns results one by one.
+interface AppDiscoveryResultsReceiver {
+  // Notifies that a result app of a Playstore app query is ready.

[Luis Héctor Chávez, 2017/06/12 21:03:59]

Mention that this is expected to be called multiple times.

[Jiaquan He, 2017/06/14 22:31:02]

Done.

+  OnResult@0(string launch_intent_uri,
+             string install_intent_uri,
+             string label,
+             bool is_instant_app,
+             bool is_recent,
+             string publisher_name,
+             array<uint8> icon_png_data);
+  // Notifies that all results are returned.
+  OnComplete@1();
+};
+
 // TODO(lhchavez): Migrate all request/response messages to Mojo.
 // Next method ID: 16
 // Deprecated method ID: 9
 interface AppInstance {
   Init@0(AppHost host_ptr);
 
   // Query if a given resolution can be handled by the application. Returns true
   // if it can.
   [MinVersion=1] CanHandleResolution@4(string package_name, string activity,
                                        ScreenRect dimension) =>
@@ skipping 53 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.
+  [MinVersion=18] GetRecentAndSuggestedApps@16(string query,

[Luis Héctor Chávez, 2017/06/12 21:03:59]

nit:

  [MinVersion=18] GetRecentAndSuggestedApps@16(
      string query, int32_t max_results,
      AppDiscoveryResultsReceiver receiver);

[Jiaquan He, 2017/06/14 22:31:02]

Changed to returning a list of results at once.

+                                               int32 max_results,
+                                               AppDiscoveryResultsReceiver receiver);
 };