Fix touch in software mirror mode when there is no internal display

ash/touch/touch_transformer_controller.cc

 // Copyright 2014 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.
 
 #include "ash/touch/touch_transformer_controller.h"
 
 #include "ash/display/display_controller.h"
 #include "ash/display/display_manager.h"
 #include "ash/host/ash_window_tree_host.h"
 #include "ash/root_window_controller.h"
@@ skipping 186 matching lines @@
   }
 
   if (display_state == ui::MULTIPLE_DISPLAY_STATE_DUAL_EXTENDED) {
     // In extended but software mirroring mode, ther is only one X root window
     // that associates with both displays.
     if (GetDisplayManager()->software_mirroring_enabled())  {
       aura::Window* root = display_controller->GetPrimaryRootWindow();
       RootWindowController::ForWindow(root)->ash_host()->UpdateDisplayID(
           display1_id, display2_id);
       DisplayInfo source_display =
-          gfx::Display::InternalDisplayId() == display1_id ?
-          display1 : display2;
+          display_controller->GetPrimaryDisplayId() == display1_id ? display1
+                                                                   : display2;

[oshima, 2015/02/27 22:13:54]

primary display can be external on the device that have internal display. I
think you need to handle both cases (use internal, or use primary when no
internal)

[pkotwicz, 2015/03/01 01:51:14]

That is true. However, in software mirror mode, if the device has an internal
display, the internal display is guaranteed to be the primary display.

The primary display is updated in DisplayController::OnDisplayRemoved()
In software mirror mode, |DisplayManager::displays_| has just one entry

[pkotwicz, 2015/03/01 03:32:50]

Even if the internal display is not the primary display in software mirror mode
and the device has an internal display, this code does the right thing.

On Ozone, the internal display is always the primary display but for very subtle
reasons. Which display is the source display / primary display depends on:
- The display IDs of both displays
- The order of |NativeDisplayDelegateDri::cached_displays_|
See
https://code.google.com/p/chromium/codesearch#chromium/src/ash/display/displa...

       // Mapping from framebuffer size to the source display's native
       // resolution.
       device_manager->UpdateTouchInfoForDisplay(
           display1_id, display1.touch_device_id(),
           GetTouchTransform(source_display, display1,
                             FindTouchscreenById(display1.touch_device_id()),
                             fb_size));
       device_manager->UpdateTouchInfoForDisplay(
           display2_id, display2.touch_device_id(),
           GetTouchTransform(source_display, display2,
@@ skipping 39 matching lines @@
 
 void TouchTransformerController::OnDisplaysInitialized() {
   UpdateTouchTransformer();
 }
 
 void TouchTransformerController::OnDisplayConfigurationChanged() {
   UpdateTouchTransformer();
 }
 
 }  // namespace ash