[Chromoting] Fix mouse when single display selected in multi-mon

Previous code would always translate the mouse coords relative to the
upper-left corner of the entire display, instead of relative to the
currently selected display.

This cl changes the mouse input scaler to be a DesktopRect instead of
a DesktopSize because we need to keep track of the origin for proper
mouse event scaling.

Change-Id: I397c51280187c7a8e023e8a41940b6f37b39eb7f
Reviewed-on: https://chromium-review.googlesource.com/c/1429339
Commit-Queue: Gary Kacmarcik <[email protected]>
Reviewed-by: Joe Downing <[email protected]>
Cr-Commit-Position: refs/heads/master@{#625325}
diff --git a/remoting/proto/control.proto b/remoting/proto/control.proto
index 1829b30..c020e6a 100644
--- a/remoting/proto/control.proto
+++ b/remoting/proto/control.proto
@@ -112,3 +112,25 @@
   // The "all" string is used to select the entire desktop.
   optional string id = 1;
 }
+
+message DesktopDisplayInfo {
+  // Unique display identifier.
+  optional int32 id = 1;
+
+  // Position of the top left corner of this display (in pixels).
+  optional int32 x = 2;
+  optional int32 y = 3;
+
+  // Size of the display (in pixels).
+  optional int32 width = 4;
+  optional int32 height = 5;
+
+  // DPI of the screen.
+  optional int32 dpi = 6;
+
+  // Bits per pixel.
+  optional int32 bpp = 7;
+
+  // True if this is the default display.
+  optional bool is_default = 8;
+}