Revert of Add support for ContentViewCore helpers on Tab

chrome/android/java/src/org/chromium/chrome/browser/TabObserver.java

Index: chrome/android/java/src/org/chromium/chrome/browser/TabObserver.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/TabObserver.java b/chrome/android/java/src/org/chromium/chrome/browser/TabObserver.java
index ca914340ef5058bd86f6a7c75a810b28f472eb48..9a7774bfed99352f16a53cb1d211b2f0d5d1c2b1 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/TabObserver.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/TabObserver.java
@@ -45,20 +45,6 @@
      * @param tab The notifying {@link Tab}.
      */
     void onContentChanged(Tab tab);
-
-    /**
-     * Called when a {@link ContentViewCore} overlay is attached to {@code tab}.
-     * @param tab     The notifying {@link Tab}.
-     * @param content The {@link ContentViewCore} being added.
-     */
-    void onOverlayContentViewCoreAdded(Tab tab, ContentViewCore content);
-
-    /**
-     * Called when a {@link ContentViewCore} overlay is detached from {@code tab}.
-     * @param tab     The notifying {@link Tab}.
-     * @param content The {@link ContentViewCore} being removed.
-     */
-    void onOverlayContentViewCoreRemoved(Tab tab, ContentViewCore content);
 
     /**
      * Called when loadUrl is triggered on a a {@link Tab}.
@@ -274,11 +260,6 @@
      */
     public void onDidDetachInterstitialPage(Tab tab);
 
-    /**
-     * Called when a navigation is started to a pending entry.
-     * @param tab The notifying {@link Tab}.
-     * @param url The url being navigated to.
-     */
     public void onDidStartNavigationToPendingEntry(Tab tab, String url);
 
     /**
@@ -288,15 +269,6 @@
      */
     public void onBackgroundColorChanged(Tab tab, int color);
 
-    /**
-     * Called when a {@link WebContents} object has been created.
-     * @param tab                 The notifying {@link Tab}.
-     * @param sourceWebContents   The {@link WebContents} that triggered the creation.
-     * @param openerRenderFrameId The opener render frame id.
-     * @param frameName           The name of the frame.
-     * @param targetUrl           The target url.
-     * @param newWebContents      The newly created {@link WebContents}.
-     */
     public void webContentsCreated(Tab tab, WebContents sourceWebContents, long openerRenderFrameId,
             String frameName, String targetUrl, WebContents newWebContents);
 }