Reland of Android: support multiple displays on C++ side

ui/android/java/src/org/chromium/ui/display/DisplayAndroidManager.java

Index: ui/android/java/src/org/chromium/ui/display/DisplayAndroidManager.java
diff --git a/ui/android/java/src/org/chromium/ui/display/DisplayAndroidManager.java b/ui/android/java/src/org/chromium/ui/display/DisplayAndroidManager.java
index dd86c1e152987fb92f81c3f873db1459a87e09d8..ea17cb7e37bf2e56dc496c66a9b552a6a6601fb2 100644
--- a/ui/android/java/src/org/chromium/ui/display/DisplayAndroidManager.java
+++ b/ui/android/java/src/org/chromium/ui/display/DisplayAndroidManager.java
@@ -17,11 +17,13 @@ import android.view.WindowManager;
 
 import org.chromium.base.ContextUtils;
 import org.chromium.base.ThreadUtils;
+import org.chromium.base.annotations.JNINamespace;
 import org.chromium.ui.gfx.DeviceDisplayInfo;
 
 /**
  * DisplayAndroidManager is a class that informs its observers Display changes.
  */
+@JNINamespace("display")
 /* package */ class DisplayAndroidManager {
     /**
      * DisplayListenerBackend is an interface that abstract the mechanism used for the actual
@@ -66,13 +68,8 @@ import org.chromium.ui.gfx.DeviceDisplayInfo;
 
         private static final long POLLING_DELAY = 500;
 
-        private int mMainSdkDisplayId;
         private int mAccurateCount;
 
-        public DisplayListenerAPI16(int sdkDisplayId) {
-            mMainSdkDisplayId = sdkDisplayId;
-        }
-
         // DisplayListenerBackend implementation:
 
         @Override
@@ -158,6 +155,13 @@ import org.chromium.ui.gfx.DeviceDisplayInfo;
 
         @Override
         public void onDisplayRemoved(int sdkDisplayId) {
+            // Never remove the primary display.
+            if (sdkDisplayId == mMainSdkDisplayId) return;
+
+            DisplayAndroid displayAndroid = mIdMap.get(sdkDisplayId);
+            if (displayAndroid == null) return;
+
+            nativeRemoveDisplay(sdkDisplayId);
             mIdMap.remove(sdkDisplayId);
         }
 
@@ -173,6 +177,7 @@ import org.chromium.ui.gfx.DeviceDisplayInfo;
 
     private static DisplayAndroidManager sDisplayAndroidManager;
 
+    private int mMainSdkDisplayId;
     private SparseArray<DisplayAndroid> mIdMap;
     private final DisplayListenerBackend mBackend;
 
@@ -207,13 +212,26 @@ import org.chromium.ui.gfx.DeviceDisplayInfo;
 
     private DisplayAndroidManager() {
         mIdMap = new SparseArray<>();
+        Display display;
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
             mBackend = new DisplayListenerBackendImpl();
+            // Make sure the display map contains the built-in primary display.
+            // The primary display is never removed.
+            display = getDisplayManager().getDisplay(Display.DEFAULT_DISPLAY);
+
+            // Android documentation on Display.DEFAULT_DISPLAY suggests that the above
+            // method might return null. In that case we retrieve the default display
+            // from the application context and take it as the primary display.
+            if (display == null) display = getDisplayFromContext(getContext());
         } else {
-            Display display = getDisplayFromContext(getContext());
-            mBackend = new DisplayListenerAPI16(display.getDisplayId());
-            addDisplay(display);  // Note this display is never removed.
+            mBackend = new DisplayListenerAPI16();
+            display = getDisplayFromContext(getContext());
         }
+
+        mMainSdkDisplayId = display.getDisplayId();
+        nativeSetPrimaryDisplayId(mMainSdkDisplayId);
+        addDisplay(display); // Note this display is never removed.
+
         mBackend.startListening();
     }
 
@@ -238,6 +256,22 @@ import org.chromium.ui.gfx.DeviceDisplayInfo;
         int sdkDisplayId = display.getDisplayId();
         DisplayAndroid displayAndroid = new DisplayAndroid(display);
         mIdMap.put(sdkDisplayId, displayAndroid);
+
+        updateDisplayOnNativeSide(displayAndroid);
         return displayAndroid;
     }
+
+    /* package */ void updateDisplayOnNativeSide(DisplayAndroid displayAndroid) {
+        nativeUpdateDisplay(displayAndroid.getSdkDisplayId(),
+                displayAndroid.getPhysicalDisplayWidth(), displayAndroid.getPhysicalDisplayHeight(),
+                displayAndroid.getDisplayWidth(), displayAndroid.getDisplayHeight(),
+                displayAndroid.getDIPScale(), displayAndroid.getRotationDegrees(),
+                displayAndroid.getBitsPerPixel(), displayAndroid.getBitsPerComponent());
+    }
+
+    private static native void nativeUpdateDisplay(int sdkDisplayId, int physicalWidth,
+            int physicalHeight, int width, int height, float dipScale, int rotationDegrees,
+            int bitsPerPixel, int bitsPerComponent);
+    private static native void nativeRemoveDisplay(int sdkDisplayId);
+    private static native void nativeSetPrimaryDisplayId(int sdkDisplayId);
 }