WebContentsObserver and TabObserver update for PlzNavigate

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

Index: chrome/android/java/src/org/chromium/chrome/browser/tab/TabObserver.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/tab/TabObserver.java b/chrome/android/java/src/org/chromium/chrome/browser/tab/TabObserver.java
index 58438a391cd77372349a793883d0b484a2034664..5a01b44d8a5cb320e027f6d41d8a93a5dff3a5cf 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/tab/TabObserver.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/tab/TabObserver.java
@@ -5,6 +5,7 @@
 package org.chromium.chrome.browser.tab;
 
 import android.graphics.Bitmap;
+import android.support.annotation.Nullable;
 import android.view.ContextMenu;
 
 import org.chromium.chrome.browser.TabLoadStatus;
@@ -242,6 +243,35 @@ public interface TabObserver {
             boolean isNavigationToDifferentPage, boolean isFragmentNavigation, int statusCode);
 
     /**
+     * Called when a navigation is started in the WebContents.
+     * @param tab The notifying {@link Tab}.
+     * @param url The validated URL for the loading page.
+     * @param isInMainFrame Whether the navigation is for the main frame.
+     * @param isErrorPage Whether the navigation shows an error page.
+     */
+    public void onDidStartNavigation(
+            Tab tab, String url, boolean isInMainFrame, boolean isErrorPage);
+
+    /**
+     * Called when a navigation is finished i.e. committed, aborted or replaced by a new one.
+     * @param tab The notifying {@link Tab}.
+     * @param url The validated URL for the loading page.
+     * @param isInMainFrame Whether the navigation is for the main frame.
+     * @param isErrorPage Whether the navigation shows an error page.
+     * @param hasCommitted Whether the navigation has committed. This returns true for either
+     *                     successful commits or error pages that replace the previous page
+     *                     (distinguished by |isErrorPage|), and false for errors that leave the
+     *                     user on the previous page.
+     * @param isSamePage Whether the main frame navigation did not cause changes to the
+     *                   document (for example scrolling to a named anchor or PopState).
+     * @param pageTransition The page transition type associated with this navigation.
+     * @param errorCode The net error code if an error occurred prior to commit, otherwise net::OK.
+     */
+    public void onDidFinishNavigation(Tab tab, String url, boolean isInMainFrame,
+            boolean isErrorPage, boolean hasCommitted, boolean isSamePage,
+            @Nullable Integer pageTransition, int errorCode);
+
+    /**
      * Called when the page has painted something non-empty.
      * @param tab The notifying {@link Tab}.
      */