Use Display changes for screen orientation changes.

content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java

Index: content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
index 04b3175e6c4116e5fef5f6039ae141ccb70469ae..8964d412cd2652904afbb248c235aeef53f807dd 100644
--- a/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
+++ b/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java
@@ -16,6 +16,7 @@ import android.graphics.Bitmap;
 import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Rect;
+import android.hardware.display.DisplayManager;
 import android.net.Uri;
 import android.os.Build;
 import android.os.Bundle;
@@ -436,6 +437,72 @@ public class ContentViewCore
     }
 
     /**
+     * DisplayManager listener used to detect screen orientation changes and
+     * inform the ContentViewCore of any change.
+     */
+    private class DisplayOrientationListener
+            implements DisplayManager.DisplayListener {
+
+        private final DisplayManager mDisplayManager;
+        private int mPreviousOrientation;
+
+        public DisplayOrientationListener(Context context) {
+            mDisplayManager =
+                    (DisplayManager) getContext().getSystemService(Context.DISPLAY_SERVICE);
+            mDisplayManager.registerDisplayListener(this, null);
+
+            mPreviousOrientation = getOrientation();
+            sendOrientationChangeEvent(mPreviousOrientation);
+        }
+
+        @Override
+        public void onDisplayAdded(int displayId) {
+        }
+
+        @Override
+        public void onDisplayChanged(int displayId) {
+            int orientation = getOrientation();
+            if (orientation == mPreviousOrientation) {
+                return;
+            }
+
+            sendOrientationChangeEvent(orientation);
+            mPreviousOrientation = orientation;
+        }
+
+        @Override
+        public void onDisplayRemoved(int displayId) {
+        }
+
+        /**
+         * Gets the screen orientation from Android.
+         */
+        private int getOrientation() {
+            WindowManager windowManager =
+                    (WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE);
+            switch (windowManager.getDefaultDisplay().getRotation()) {
+                case Surface.ROTATION_90:
+                    return 90;
+                case Surface.ROTATION_180:
+                    return 180;
+                case Surface.ROTATION_270:
+                    return -90;
+                case Surface.ROTATION_0:
+                    return 0;
+                default:
+                    throw new IllegalStateException(
+                            "Display.getRotation() shouldn't return that value");
+            }
+        }
+
+        private void destroy() {
+            mDisplayManager.unregisterDisplayListener(this);
+        }
+    }
+
+    private DisplayOrientationListener mDisplayListener;
+
+    /**
      * Used by UMA stat for tracking accidental double tap navigations. Specifies the amount of
      * time after a double tap within which actions will be recorded to the UMA stat.
      */
@@ -720,8 +787,6 @@ public class ContentViewCore
                 resetGestureDetectors();
             }
         };
-
-        sendOrientationChangeEvent();
     }
 
     @CalledByNative
@@ -1578,6 +1643,8 @@ public class ContentViewCore
     @SuppressWarnings("javadoc")
     public void onAttachedToWindow() {
         setAccessibilityState(mAccessibilityManager.isEnabled());
+
+        mDisplayListener = new DisplayOrientationListener(mContext);
     }
 
     /**
@@ -1589,6 +1656,9 @@ public class ContentViewCore
         hidePopupDialog();
         mZoomControlsDelegate.dismissZoomPicker();
         unregisterAccessibilityContentObserver();
+
+        mDisplayListener.destroy();
+        mDisplayListener = null;
     }
 
     /**
@@ -1643,15 +1713,7 @@ public class ContentViewCore
             manager.restartInput(mContainerView);
         }
         mContainerViewInternals.super_onConfigurationChanged(newConfig);
-        // Make sure the size is up to date in JavaScript's window.onorientationchanged.
-        mContainerView.addOnLayoutChangeListener(new View.OnLayoutChangeListener() {
-            @Override
-            public void onLayoutChange(View v, int left, int top, int right, int bottom,
-                    int oldLeft, int oldTop, int oldRight, int oldBottom) {
-                mContainerView.removeOnLayoutChangeListener(this);
-                sendOrientationChangeEvent();
-            }
-        });
+
         // To request layout has side effect, but it seems OK as it only happen in
         // onConfigurationChange and layout has to be changed in most case.
         mContainerView.requestLayout();
@@ -2124,32 +2186,12 @@ public class ContentViewCore
     }
 
     /**
-     * Get the screen orientation from the OS and push it to WebKit.
-     *
-     * TODO(husky): Add a hook for mock orientations.
+     * Send the screen orientation value to the renderer.
      */
-    private void sendOrientationChangeEvent() {
+    private void sendOrientationChangeEvent(int orientation) {
         if (mNativeContentViewCore == 0) return;
 
-        WindowManager windowManager =
-                (WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE);
-        switch (windowManager.getDefaultDisplay().getRotation()) {
-            case Surface.ROTATION_90:
-                nativeSendOrientationChangeEvent(mNativeContentViewCore, 90);
-                break;
-            case Surface.ROTATION_180:
-                nativeSendOrientationChangeEvent(mNativeContentViewCore, 180);
-                break;
-            case Surface.ROTATION_270:
-                nativeSendOrientationChangeEvent(mNativeContentViewCore, -90);
-                break;
-            case Surface.ROTATION_0:
-                nativeSendOrientationChangeEvent(mNativeContentViewCore, 0);
-                break;
-            default:
-                Log.w(TAG, "Unknown rotation!");
-                break;
-        }
+        nativeSendOrientationChangeEvent(mNativeContentViewCore, orientation);
     }
 
     /**