linux/x11: Fix event dispatch in menus in High DPI.

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.cc

 // 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.
 
 #include "ui/views/widget/desktop_aura/desktop_window_tree_host_x11.h"
 
 #include <X11/extensions/shape.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/Xatom.h>
 #include <X11/Xregion.h>
@@ skipping 1414 matching lines @@
   // While we unset the urgency hint when we gain focus, we also must remove it
   // on mouse clicks because we can call FlashFrame() on an active window.
   if (event->IsAnyButton() || event->IsMouseWheelEvent())
     FlashFrame(false);
 
   if (!g_current_capture || g_current_capture == this) {
     SendEventToProcessor(event);
   } else {
     // Another DesktopWindowTreeHostX11 has installed itself as
     // capture. Translate the event's location and dispatch to the other.
-    event->ConvertLocationToTarget(window(), g_current_capture->window());
+    UpdateEventLocationForDifferentHost(event, g_current_capture);
     g_current_capture->SendEventToProcessor(event);
   }
 }
 
 void DesktopWindowTreeHostX11::DispatchTouchEvent(ui::TouchEvent* event) {
   if (g_current_capture && g_current_capture != this &&
       event->type() == ui::ET_TOUCH_PRESSED) {
-    event->ConvertLocationToTarget(window(), g_current_capture->window());
+    UpdateEventLocationForDifferentHost(event, g_current_capture);
     g_current_capture->SendEventToProcessor(event);
   } else {
     SendEventToProcessor(event);
   }
 }
 
+void DesktopWindowTreeHostX11::UpdateEventLocationForDifferentHost(

[pkotwicz, 2015/02/13 20:15:35]

Nit: I think that ConvertEventToDifferentHost() is clearer.

[sadrul, 2015/02/13 20:27:36]

Done.

+    ui::LocatedEvent* located_event,
+    DesktopWindowTreeHostX11* host) {
+  DCHECK_NE(this, host);
+  const gfx::Display display_src =
+      gfx::Screen::GetNativeScreen()->GetDisplayNearestWindow(window());
+  const gfx::Display display_dest =
+      gfx::Screen::GetNativeScreen()->GetDisplayNearestWindow(host->window());
+  DCHECK_EQ(display_src.device_scale_factor(),
+            display_dest.device_scale_factor());
+  gfx::Vector2d offset = GetLocationOnNativeScreen() -
+                         g_current_capture->GetLocationOnNativeScreen();

[pkotwicz, 2015/02/13 20:15:35]

g_current_capture -> host

[sadrul, 2015/02/13 20:27:36]

whoops. Done.

+  gfx::Point location_in_pixel = located_event->location() + offset;

[pkotwicz, 2015/02/13 20:15:35]

Nit: This variable name is confusing. Is "pixel" the name of yet another
coordinate system? Maybe rename |host| to |other_host| and rename
|location_in_pixel| to |location_in_other_host|

[sadrul, 2015/02/13 20:27:36]

'pixel' here means 'physical pixels' (for device-independent pixels). We use
_in_pixel (and _in_dip) suffixes in a lot of ui code to mean these coord space.
I want to be explicit here too that the location here is in physical pixel
space.

Renamed to location_in_pixel_in_host (since |host| is the variable name).

[sadrul, 2015/02/13 20:31:09]

Should read: "'pixel' here means 'physical pixels' (*as opposed to*
device-independent pixels). ..."

+  located_event->set_location(location_in_pixel);
+}
+
 void DesktopWindowTreeHostX11::ResetWindowRegion() {
   // If a custom window shape was supplied then apply it.
   if (custom_window_shape_) {
     XShapeCombineRegion(
         xdisplay_, xwindow_, ShapeBounding, 0, 0, window_shape_, false);
     return;
   }
 
   if (window_shape_)
     XDestroyRegion(window_shape_);
@@ skipping 471 matching lines @@
   if (linux_ui) {
     ui::NativeTheme* native_theme = linux_ui->GetNativeTheme(window);
     if (native_theme)
       return native_theme;
   }
 
   return ui::NativeTheme::instance();
 }
 
 }  // namespace views