Add touch events to the protocol, the stub layer, and to the client plugin.

remoting/proto/event.proto

Index: remoting/proto/event.proto
diff --git a/remoting/proto/event.proto b/remoting/proto/event.proto
index dd150942b771df1fab75e72512bac3d28ded5a6b..28fd80b8221746d178fdc2c72dfe578e45c94ed8 100644
--- a/remoting/proto/event.proto
+++ b/remoting/proto/event.proto
@@ -1,4 +1,4 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+ // Copyright (c) 2012 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.
 
@@ -79,3 +79,56 @@ message ClipboardEvent {
   // The data being sent.
   optional bytes data = 2;
 }
+
+message TouchEventPoint {
+
+  // The ID for the touch point.
+  optional uint32 id = 1;
+
+  // The position of the touch point.
+  // These values on-the-wire are host coordinates.
+  optional float x = 2;
+  optional float y = 3;

[Wez, 2015/02/05 02:09:07]

nit: Do these need to be floats? Chromoting works in device-pixel coordinates
(versus logical-pixel), so whereas logical pixel positions can be fractional on
a high-DPI device, ours can't.

[Rintaro Kuroiwa, 2015/02/06 23:35:01]

As discussed offline.
Some touch event APIs mention that some digitizers can detect sub-pixel
coordinates and would be reported as floating point numbers.

+
+  // The size of the touch point, used to aid hit-testing.
+  // Scaled to match the size on host.
+  optional float radius_x = 4;
+  optional float radius_y = 5;
+
+  // Angle in degrees from the y-axis of the touch point.
+  optional float angle = 6;
+
+  // The pressure of the touch point.
+  // The value should be in [0.0, 1.0].
+  optional float pressure = 7;
+}
+
+message TouchEvent {
+
+  // A START event means that this event reports all the touch points that were
+  // just added, e.g. a finger started touching the display.
+  // A MOVE event means that the touch points that have been STARTed moved,
+  // e.g. multiple fingers on the screen moved.
+  // An END event means that the touch points that have been STARTed ended.
+  // e.g. a finger went off the screen.
+  // A CANCEL event means that the touch points that have been STARTed were
+  // canceled, e.g. a finger went off the screen.
+  // Cancel event is simlar to END but slighly different. For example, Android
+  // MotionEvent's ACTION_CANCEL documentation mentions that a cancel should be
+  // treated as an ACTION_UP (END) event but might not perform the exact same
+  // actions as a normal ACTION_UP event.
+  enum TouchEventType {
+    TOUCH_POINT_START = 1;
+    TOUCH_POINT_MOVE = 2;
+    TOUCH_POINT_END = 3;
+    TOUCH_POINT_CANCEL = 4;
+  };
+
+  optional TouchEventType event_type = 1;
+
+  // Only the changed touch points are added to this field.
+  // Given the existing touch point APIs (e.g. Android and PPAPI)
+  // for START, END, and CANCEL events the size of this field will typically be
+  // 1, but for MOVE events it is likely to have multiple points.
+  repeated TouchEventPoint touch_points = 2;
+}