Migrate IME state update flow

chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java

Index: chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java b/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
index ed0bc3c71ce1d32da7413075e15f9a9f9cac92cf..d3de2ebd4f8698e44b0f77ab109acb9a64c2e573 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/tab/Tab.java
@@ -94,6 +94,7 @@ import org.chromium.content.browser.ContentViewClient;
 import org.chromium.content.browser.ContentViewCore;
 import org.chromium.content.browser.crypto.CipherFactory;
 import org.chromium.content_public.browser.GestureStateListener;
+import org.chromium.content_public.browser.ImeEventObserver;
 import org.chromium.content_public.browser.LoadUrlParams;
 import org.chromium.content_public.browser.WebContents;
 import org.chromium.content_public.common.BrowserControlsState;
@@ -374,20 +375,6 @@ public class Tab
 
     private class TabContentViewClient extends ContentViewClient {
         @Override
-        public void onImeEvent() {
-            // Some text was set in the page. Don't reuse it if a tab is
-            // open from the same external application, we might lose some
-            // user data.
-            mAppAssociatedWith = null;
-        }
-
-        @Override
-        public void onFocusedNodeEditabilityChanged(boolean editable) {
-            if (getFullscreenManager() == null) return;
-            updateFullscreenEnabledState();
-        }
-
-        @Override
         public int getSystemWindowInsetBottom() {
             ChromeActivity activity = getActivity();
             if (activity != null && activity.getInsetObserverView() != null) {
@@ -1327,6 +1314,22 @@ public class Tab
                 setContentViewCore(contentViewCore);
             }
 
+            mContentViewCore.addImeEventObserver(new ImeEventObserver() {
+                @Override
+                public void onImeEvent() {
+                    // Some text was set in the page. Don't reuse it if a tab is
+                    // open from the same external application, we might lose some
+                    // user data.
+                    mAppAssociatedWith = null;
+                }
+
+                @Override
+                public void onNodeAttributeUpdated(boolean editable, boolean password) {
+                    if (getFullscreenManager() == null) return;
+                    updateFullscreenEnabledState();
+                }
+            });
+
             if (!creatingWebContents && webContents.isLoadingToDifferentDocument()) {
                 didStartPageLoad(webContents.getUrl(), false);
             }