exo: Use panel rotation for drawing/reporting

panel_rotation() is the difference between the buffer and hardware's
scanlines as opposed to rotation() which is the "logical" uprightness
of the screen. This matters on devices where the logical orientation
does not match the hardware orientation.

There are two cases where exo uses the wrong rotation which means:
 - cursor images are drawn in the wrong orientation
 - the screen orientation is reported incorrectly to clients. This is
   ~fine~ until you start using applications which refuse to handle
   events which are "offscreen".

We model this CL after changes in crrev.com/c/1911344.

Bug: 1081085
Change-Id: Ia3a01b8dd5d745dbdb6a5b2220cae44061088a77
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2195341Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Commit-Queue: Nic Hollingum <hollingum@google.com>
Cr-Commit-Position: refs/heads/master@{#769038}

components/exo/pointer.cc

@@ -678,7 +678,9 @@ void Pointer::UpdateCursor() {
     if (cursor_client->GetCursorSize() == ui::CursorSize::kLarge)
       scale *= kLargeCursorScale;
 
-    ui::ScaleAndRotateCursorBitmapAndHotpoint(scale, display.rotation(),
+    // Use panel_rotation() rather than "natural" rotation, as it actually
+    // relates to the hardware you're about to draw the cursor bitmap on.
+    ui::ScaleAndRotateCursorBitmapAndHotpoint(scale, display.panel_rotation(),
                                               &bitmap, &hotspot);
 
     ui::PlatformCursor platform_cursor;

components/exo/wayland/wayland_display_observer.cc

@@ -81,13 +81,15 @@ void WaylandDisplayObserver::SendDisplayMetrics() {
   // has raw information before overscan, rotation applied.
   gfx::Size size_in_pixel = display.GetSizeInPixel();
 
+  // Use panel_rotation otherwise some X apps will refuse to take events from
+  // outside the "visible" region.
   wl_output_send_geometry(
       output_resource_, origin.x(), origin.y(),
       static_cast<int>(kInchInMm * size_in_pixel.width() / info.device_dpi()),
       static_cast<int>(kInchInMm * size_in_pixel.height() / info.device_dpi()),
       WL_OUTPUT_SUBPIXEL_UNKNOWN, make.empty() ? kUnknown : make.c_str(),
       model.empty() ? kUnknown : model.c_str(),
-      OutputTransform(display.rotation()));
+      OutputTransform(display.panel_rotation()));
 
   if (wl_resource_get_version(output_resource_) >=
       WL_OUTPUT_SCALE_SINCE_VERSION) {