DialogSurfaceManager implementation.

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 87d4533b103cdbda38129a887284a03a6e6259fe..46a82102158bd56e18640f9fc015e5fc65b5e304 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
@@ -98,6 +98,21 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Displa
     // produce little visible difference.
     private static final float ZOOM_CONTROLS_EPSILON = 0.007f;
 
+    /**
+     * Observer for changes to WindowAndroid.  Mirrors
+     * ContentViewCoreImplObserver in native.  Appends 'Android' to (a) match
+     * WindowAndroid, and (b) avoid a name collision with View.
+     */
+    public interface Observer {
+        public void onContentViewCoreDestroyed(ContentViewCore cvc);
+        public void onAttachedToWindowAndroid(ContentViewCore cvc);
+        public void onDetachedFromWindowAndroid(ContentViewCore cvc);
+    }
+
+    // Single observer.  We only support one right now, since we have only one
+    // consumer of it.
+    private Observer mObserver;
+
     // If the embedder adds a JavaScript interface object that contains an indirect reference to
     // the ContentViewCore, then storing a strong ref to the interface object on the native
     // side would prevent garbage collection of the ContentViewCore (as that strong ref would
@@ -704,6 +719,7 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Displa
     private void onNativeContentViewCoreDestroyed(long nativeContentViewCore) {
         assert nativeContentViewCore == mNativeContentViewCore;
         mNativeContentViewCore = 0;
+        if (mObserver != null) mObserver.onContentViewCoreDestroyed(this);
     }
 
     /**
@@ -2813,6 +2829,31 @@ public class ContentViewCore implements AccessibilityStateChangeListener, Displa
         return mShowKeyboardResultReceiver;
     }
 
+    // Set our observer.  We support only a single observer right now.  If
+    // |observer| is already an observer, then do nothing.
+    public void addObserver(Observer observer) {
+        assert mObserver == null || mObserver == observer;
+        mObserver = observer;
+    }
+
+    // Remove our single observer.
+    public void removeObserver(Observer observer) {
+        assert mObserver == observer;
+        // Note that this can be called as part of a callback, so be careful if
+        // we're iterating over a list of observers when this is called.
+        mObserver = null;
+    }
+
+    @CalledByNative
+    private void onAttachedToWindowAndroid() {
+        if (mObserver != null) mObserver.onAttachedToWindowAndroid(this);

[boliu, 2017/01/04 23:14:39]

sigh.. I should really unify these two different "attachToWindow" code paths,
there is no reason they are different

also, taking a step back, we are trying to get rid of ContentViewCore, so adding
more things here is not ideal. the attach/detach event observer probably should
live on ViewAndroid (which only exists in c++ code, though there is no reason it
can't have java observers..)

[liberato (no reviews please), 2017/01/11 22:17:56]

i didn't see an obvious way to do this.  i'll re-check, and probably chat
offline to see how to proceed.

+    }
+
+    @CalledByNative
+    private void onDetachedFromWindowAndroid() {
+        if (mObserver != null) mObserver.onDetachedFromWindowAndroid(this);
+    }
+
     private native long nativeInit(WebContents webContents, ViewAndroidDelegate viewAndroidDelegate,
             long windowAndroidPtr, float dipScale, HashSet<Object> retainedObjectSet);
     private static native ContentViewCore nativeFromWebContentsAndroid(WebContents webContents);