Introduce ViewRoot forwarding input/view events to native

content/shell/android/java/src/org/chromium/content_shell/Shell.java

 // Copyright 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.
 
 package org.chromium.content_shell;
 
 import android.app.Activity;
 import android.content.Context;
 import android.graphics.drawable.ClipDrawable;
 import android.text.TextUtils;
@@ skipping 19 matching lines @@
 import org.chromium.content.browser.ContentVideoViewEmbedder;
 import org.chromium.content.browser.ContentView;
 import org.chromium.content.browser.ContentViewClient;
 import org.chromium.content.browser.ContentViewCore;
 import org.chromium.content.browser.ContentViewRenderView;
 import org.chromium.content_public.browser.ActionModeCallbackHelper;
 import org.chromium.content_public.browser.LoadUrlParams;
 import org.chromium.content_public.browser.NavigationController;
 import org.chromium.content_public.browser.WebContents;
 import org.chromium.ui.base.ViewAndroidDelegate;
+import org.chromium.ui.base.ViewRoot;
 import org.chromium.ui.base.WindowAndroid;
 
 /**
  * Container for the various UI components that make up a shell window.
  */
 @JNINamespace("content")
 public class Shell extends LinearLayout {
 
     private static final long COMPLETED_PROGRESS_TIMEOUT_MS = 200;
 
@@ skipping 240 matching lines @@
      * Initializes the ContentView based on the native tab contents pointer passed in.
      * @param webContents A {@link WebContents} object.
      */
     @SuppressWarnings("unused")
     @CalledByNative
     private void initFromNativeTabContents(WebContents webContents) {
         Context context = getContext();
         mContentViewCore = new ContentViewCore(context, "");
         ContentView cv = ContentView.createContentView(context, mContentViewCore);
         mContentViewCore.initialize(ViewAndroidDelegate.createBasicDelegate(cv), cv,
-                webContents, mWindow);
+                webContents, ViewRoot.create(mWindow));

[boliu, 2017/01/05 19:09:28]

first question is what calls destroy?

Then after digging, the right thing here again is that ViewRoot should be
created *next* to where WindowAndroid is created, so in this case, in
ContentShellActivity. However, then also realized that WindowAndroid isn't
destroyed either, which is an existing bug.

I still haven't read other embedders (other than webview) yet, but make sure
destroy is called in all the places

[Jinsuk Kim, 2017/01/05 22:30:15]

Shouldn't it be created where 'content' is created? Though in this embedder WA :
VR is 1-1 there relationship is 1-multiple in general, and view root is created
per content.

But then in the latest comments I can see that the discussion you guys had kind
of concluded it is rather per-tab (or CompositorView) where there can be
multiple contents (overlay panel for contextual search, mobile view, etc) -
specifically for Chrome. 

I still can't get my head around how a single ViewRoot can deal with multiple
web contents. I'll come up with either a new patch or a new question soon.
Done. destroyed when Shell (and its CVC) is destroyed for now.

[boliu, 2017/01/05 22:39:38]

No, except webview. If it weren't for webview, ViewRoot and WindowAndroid would
be the same class. Which means other than webview, ViewRoot and WindowAndroid
should have the exact same life time.

         mContentViewCore.setActionModeCallback(defaultActionCallback());
         mContentViewCore.setContentViewClient(mContentViewClient);
         mWebContents = mContentViewCore.getWebContents();
         mNavigationController = mWebContents.getNavigationController();
         if (getParent() != null) mContentViewCore.onShow();
         if (mWebContents.getUrl() != null) {
             mUrlTextView.setText(mWebContents.getUrl());
         }
         ((FrameLayout) findViewById(R.id.contentview_holder)).addView(cv,
                 new FrameLayout.LayoutParams(
@@ skipping 93 matching lines @@
                 Context.INPUT_METHOD_SERVICE);
         if (visible) {
             imm.showSoftInput(mUrlTextView, InputMethodManager.SHOW_IMPLICIT);
         } else {
             imm.hideSoftInputFromWindow(mUrlTextView.getWindowToken(), 0);
         }
     }
 
     private static native void nativeCloseShell(long shellPtr);
 }