Make DeviceDisplayInfo a Singleton and have ScreenOrientationListener update it.

ui/android/java/src/org/chromium/ui/gfx/DeviceDisplayInfo.java

Index: ui/android/java/src/org/chromium/ui/gfx/DeviceDisplayInfo.java
diff --git a/ui/android/java/src/org/chromium/ui/gfx/DeviceDisplayInfo.java b/ui/android/java/src/org/chromium/ui/gfx/DeviceDisplayInfo.java
index 863fa1b5e16d41c2a6fbbceb807823ed8af87af8..98f51507bee9e004a26fc51356b51702704e8ce5 100644
--- a/ui/android/java/src/org/chromium/ui/gfx/DeviceDisplayInfo.java
+++ b/ui/android/java/src/org/chromium/ui/gfx/DeviceDisplayInfo.java
@@ -4,9 +4,7 @@
 
 package org.chromium.ui.gfx;
 
-import android.content.ComponentCallbacks;
 import android.content.Context;
-import android.content.res.Configuration;
 import android.graphics.PixelFormat;
 import android.graphics.Point;
 import android.os.Build;
@@ -28,6 +26,8 @@ import org.chromium.base.JNINamespace;
 public class DeviceDisplayInfo {
 
 
+    private static DeviceDisplayInfo sInstance;
+
     private final Context mAppContext;
     private final WindowManager mWinManager;
     private Point mTempPoint = new Point();
@@ -42,7 +42,8 @@ public class DeviceDisplayInfo {
      */
     @CalledByNative
     public int getDisplayHeight() {
-        return getMetrics().heightPixels;
+        getDisplay().getSize(mTempPoint);
+        return mTempPoint.y;
     }
 
     /**
@@ -50,7 +51,8 @@ public class DeviceDisplayInfo {
      */
     @CalledByNative
     public int getDisplayWidth() {
-        return getMetrics().widthPixels;
+        getDisplay().getSize(mTempPoint);
+        return mTempPoint.x;
     }
 
     /**
@@ -79,11 +81,8 @@ public class DeviceDisplayInfo {
 
     @SuppressWarnings("deprecation")
     private int getPixelFormat() {
-        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN_MR1) {
-            return getDisplay().getPixelFormat();
-        }
-        // JellyBean MR1 and later always uses RGBA_8888.
-        return PixelFormat.RGBA_8888;
+        // API Level newer than JELLY_BEAN_MR1 will always return RGBA_8888.
+        return getDisplay().getPixelFormat();
     }
 
     /**
@@ -140,7 +139,9 @@ public class DeviceDisplayInfo {
      */
     @CalledByNative
     public double getDIPScale() {
-        return getMetrics().density;
+        DisplayMetrics metrics = new DisplayMetrics();
+        getDisplay().getMetrics(metrics);
+        return metrics.density;
     }
 
     /**
@@ -152,21 +153,7 @@ public class DeviceDisplayInfo {
         return mAppContext.getResources().getConfiguration().smallestScreenWidthDp;
     }
 
-    private void registerListener() {
-        mAppContext.registerComponentCallbacks(
-                new ComponentCallbacks() {
-                    @Override
-                    public void onConfigurationChanged(Configuration configuration) {
-                        updateNativeSharedDisplayInfo();
-                    }
-
-                    @Override
-                    public void onLowMemory() {
-                    }
-                });
-    }
-
-    private void updateNativeSharedDisplayInfo() {
+    public void updateNativeSharedDisplayInfo() {
         nativeUpdateSharedDeviceDisplayInfo(
                 getDisplayHeight(), getDisplayWidth(),
                 getPhysicalDisplayHeight(), getPhysicalDisplayWidth(),
@@ -178,25 +165,24 @@ public class DeviceDisplayInfo {
         return mWinManager.getDefaultDisplay();
     }
 
-    private DisplayMetrics getMetrics() {
-        return mAppContext.getResources().getDisplayMetrics();
-    }
-
     /**
-     * Creates DeviceDisplayInfo for a given Context.
+     * Return the DeviceDisplayInfo associated with that context and process.
+     * In practice, we use the application context which is the same for all the
+     * contexts from a given process.
+     * TODO(mlamouri): we might want to handle multiple Display, see http://crbug.com/310763
      *
      * @param context A context to use.
      * @return DeviceDisplayInfo associated with a given Context.
      */
-    public static DeviceDisplayInfo create(Context context) {
-        return new DeviceDisplayInfo(context);
-    }
-
     @CalledByNative
-    private static DeviceDisplayInfo createWithListener(Context context) {
-        DeviceDisplayInfo deviceDisplayInfo = new DeviceDisplayInfo(context);
-        deviceDisplayInfo.registerListener();
-        return deviceDisplayInfo;
+    public static DeviceDisplayInfo getInstance(Context context) {
+        if (sInstance == null) {
+            sInstance = new DeviceDisplayInfo(context);
+        }
+
+        assert context.getApplicationContext() == sInstance.mAppContext;
+
+        return sInstance;
     }
 
     private native void nativeUpdateSharedDeviceDisplayInfo(