Revert of 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 d3de2ebd4f8698e44b0f77ab109acb9a64c2e573..ed0bc3c71ce1d32da7413075e15f9a9f9cac92cf 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
@@ -94,7 +94,6 @@
 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;
@@ -374,6 +373,20 @@
     private boolean mIsAllowedToReturnToExternalApp;
 
     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();
@@ -1313,22 +1326,6 @@
             } else {
                 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);