arc-bridge: Move most methods to Mojo interfaces

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.
+
+module arc;
+
+// Duplicates ui::ScaleFactor enum in order to be accessible on Android side.
+enum ScaleFactor {
+  SCALE_FACTOR_NONE = 0,

[hidehiko, 2015/12/16 18:34:03]

nit: maybe it's time to remove the common prefix as we do for other enums (even
they are just a copy from somewhere)?
I'm fine to do this in a separate CL.

+  SCALE_FACTOR_100P,
+  SCALE_FACTOR_125P,
+  SCALE_FACTOR_133P,
+  SCALE_FACTOR_140P,
+  SCALE_FACTOR_150P,
+  SCALE_FACTOR_180P,
+  SCALE_FACTOR_200P,
+  SCALE_FACTOR_250P,
+  SCALE_FACTOR_300P,
+
+  NUM_SCALE_FACTORS
+};
+
+// Describes ARC app.
+struct AppInfo {
+  string name;
+  string package;
+  string activity;
+};
+
+interface AppHost {
+  // Receives a list of available ARC apps to Chrome. Members of AppInfo must
+  // contain non-empty string.
+  OnAppListRefreshed(array<AppInfo> apps);
+
+  // Receives an icon of required |scale_factor| for specific ARC app. The app
+  // is defined by |package| and |activity|. The icon content cannot be empty
+  // and must match to |scale_factor| assuming 48x48 for SCALE_FACTOR_100P.
+  // |scale_factor| is an enum defined at ui/base/layout.h. |icon_png_data| is
+  // a png-encoded image.
+  OnAppIcon(string package, string activity,
+            ScaleFactor scale_factor, array<uint8> icon_png_data);
+};
+
+// TODO(lhchavez): Migrate all request/response messages to Mojo.

[hidehiko, 2015/12/16 18:34:03]

You've done already?

[Luis Héctor Chávez, 2015/12/16 19:09:49]

What I want to be able to do is to change the methods to be

RefreshAppList() => (array<AppInfo> apps);
RequestAppIcon(string package, string activity, ScaleFactor scale_factor) =>
(array<uint8> icon_png_data);

+interface AppInstance {
+  Init(AppHost host_ptr);
+
+  // Sends a request to ARC to launch an ARC app defined by |package| and
+  // |activity|, which cannot be empty.
+  LaunchApp(string package, string activity);
+
+  // Sends a request to ARC to refresh a list of ARC apps.
+  // OnRefreshAppsList is expected in response to this message. However,
+  // response may not be sent if ARC is not ready yet (boot completed event is
+  // not received).
+  RefreshAppList();
+
+  // Sends a request to ARC for the ARC app icon of a required scale factor.
+  // Scale factor is an enum defined at ui/base/layout.h. App is defined by
+  // package and activity, which cannot be empty.
+  RequestAppIcon(string package, string activity, ScaleFactor scale_factor);
+};