Make WebView work for external displays (over Presentations).

ui/gfx/android/device_display_info.h

 // 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.
 
 #ifndef UI_GFX_ANDROID_DEVICE_DISPLAY_INFO_H_
 #define UI_GFX_ANDROID_DEVICE_DISPLAY_INFO_H_
 
 #include <jni.h>
 #include <string>
 
+#include "base/android/jni_android.h"
 #include "base/basictypes.h"
 #include "ui/gfx/gfx_export.h"
 
 namespace gfx {
 
 // Facilitates access to device information typically only
 // available using the Android SDK, including Display properties.
 class GFX_EXPORT DeviceDisplayInfo {
  public:
   DeviceDisplayInfo();
+  explicit DeviceDisplayInfo(jobject windowAndroid);

[boliu, 2015/06/01 15:30:18]

Can this be the native WindowAndroid type instead?

[gsennton, 2015/06/04 14:10:29]

I get a presubmit error if I try to include ui/android/window_android.h in this
file:

You added one or more #includes that violate checkdeps rules.
  ui/gfx/android/device_display_info.h
      Illegal include: "ui/android/window_android.h"
    Because of "-ui" from ui's include_rules.

[boliu, 2015/06/05 04:57:51]

Right, I have to internalize that ui/gfx is actually at a *lower* level than
everything else in ui, including ui/base. Kinda weird.

That means layering is wrong here. And having a jobject windowAndroid is
basically cheating to get around the layering problem.

So lower layers cannot depend on higher layers. Which means this class should
know nothing about WindowAndroid, java or native. Maybe it should be a context
instead.

It's tricker beacuse having the Context be owned by a higher layer object is the
wrong thing here. I don't know ui/gfx that well, but glancing through classes,
display might make more sense to be holding context. I have no idea if android
actually uses that though..

(Pretty much everyone else uses ui/views for native UI, but android uses android
views, so android does weird things here)

   ~DeviceDisplayInfo();
 
   // Returns display height in physical pixels.
   int GetDisplayHeight();
 
   // Returns display width in physical pixels.
   int GetDisplayWidth();
 
   // Returns real display height in physical pixels.
   // This version does not subtract window decorations etc.
@@ skipping 18 matching lines @@
   double GetDIPScale();
 
   // Smallest possible screen size in density-independent pixels.
   int GetSmallestDIPWidth();
 
   // Returns the display rotation angle from its natural orientation. Expected
   // values are one of { 0, 90, 180, 270 }.
   // See DeviceDispayInfo.java for more information.
   int GetRotationDegrees();
 
+  // Registers methods with JNI and returns true if succeeded.
+  static bool RegisterDeviceDisplayInfo(JNIEnv* env);
+
+ private:
+  void UpdateDisplayInfo(jint display_height,
+                         jint display_width,
+                         jint physical_display_height,
+                         jint physical_display_width,
+                         jint bits_per_pixel,
+                         jint bits_per_component,
+                         jdouble dip_scale,
+                         jint smallest_dip_width,
+                         jint rotation_degrees);
+
+  base::android::ScopedJavaGlobalRef<jobject> j_device_info_;
+
+  int display_height_;
+  int display_width_;
+  int physical_display_height_;
+  int physical_display_width_;
+  int bits_per_pixel_;
+  int bits_per_component_;
+  double dip_scale_;
+  int smallest_dip_width_;
+  int rotation_degrees_;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(DeviceDisplayInfo);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_ANDROID_DEVICE_DISPLAY_INFO_H_