Make Display's rotation and WebScreenInfo rotation work together on Aura.

content/browser/renderer_host/render_widget_host_view_aura.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 "content/browser/renderer_host/render_widget_host_view_aura.h"
 
 #include "base/auto_reset.h"
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ skipping 282 matching lines @@
 void GetScreenInfoForWindow(WebScreenInfo* results, aura::Window* window) {
   const gfx::Display display = window ?
       gfx::Screen::GetScreenFor(window)->GetDisplayNearestWindow(window) :
       gfx::Screen::GetScreenFor(window)->GetPrimaryDisplay();
   results->rect = display.bounds();
   results->availableRect = display.work_area();
   // TODO(derat|oshima): Don't hardcode this. Get this from display object.
   results->depth = 24;
   results->depthPerComponent = 8;
   results->deviceScaleFactor = display.device_scale_factor();
+
+  // The Display rotation and the WebScreenInfo orientation are not the same

[sky, 2014/06/16 20:18:42]

Are you saying the webkit rotation is relative to the physical rotation? If you
need to rotate an additional 180 (which is what you're doing), why isn't 180
special cased?

[mlamouri (slow - plz ping), 2014/06/16 20:23:27]

The value is Blink is the rotation of the rendering relative to the display
(screen). When the value is 0, the rendering isn't rotated to be displayed
correctly. When the display is rotated of 180 degrees, we need to rotate the
screen of 180 degrees to see the content correctly. However, when the display is
rotated of 90 degrees, we need to rotate it of -90 degrees to see the content
correctly. We don't want negative values so it becomes 270. For 270, we need to
rotate of -270, or 90.

[sky, 2014/06/16 20:53:02]

I got it. Can you clarify here that webscreeninfo is relative to physical. That
would help my understanding of it.

[mlamouri (slow - plz ping), 2014/06/16 21:07:29]

By the way, WebScreenInfo behaves like that because it is the only real solution
for mobile devices: the physical rotation is different from the content's
rotation. Do you know if Aura is consistent with that kind of stuff? For
example, with Windows 8?

+  // angle. The former is the physical display rotation while the later is the
+  // rotation required by the content to be shown properly on the screen, in
+  // other words, the opposite of the rotation as described by Display.
   results->orientationAngle = display.RotationAsDegree();
+  if (results->orientationAngle == 90)
+    results->orientationAngle = 270;
+  else if (results->orientationAngle == 270)
+    results->orientationAngle = 90;
 }
 
 bool PointerEventActivates(const ui::Event& event) {
   if (event.type() == ui::ET_MOUSE_PRESSED)
     return true;
 
   if (event.type() == ui::ET_GESTURE_BEGIN) {
     const ui::GestureEvent& gesture =
         static_cast<const ui::GestureEvent&>(event);
     return gesture.details().touch_points() == 1;
@@ skipping 2066 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewBase, public:
 
 // static
 void RenderWidgetHostViewBase::GetDefaultScreenInfo(WebScreenInfo* results) {
   GetScreenInfoForWindow(results, NULL);
 }
 
 }  // namespace content