WebContentsObserver and TabObserver update for PlzNavigate

content/public/android/java/src/org/chromium/content_public/browser/WebContentsObserver.java

Index: content/public/android/java/src/org/chromium/content_public/browser/WebContentsObserver.java
diff --git a/content/public/android/java/src/org/chromium/content_public/browser/WebContentsObserver.java b/content/public/android/java/src/org/chromium/content_public/browser/WebContentsObserver.java
index c947e078e6a61e0294c718f9262f09bd2f6c62fd..641128d36a0ff9eb3875ecfa39648f5ef5517079 100644
--- a/content/public/android/java/src/org/chromium/content_public/browser/WebContentsObserver.java
+++ b/content/public/android/java/src/org/chromium/content_public/browser/WebContentsObserver.java
@@ -30,17 +30,30 @@ public abstract class WebContentsObserver {
     public void renderProcessGone(boolean wasOomProtected) {}
 
     /**
-     * Called when the current navigation finishes.
-     *
-     * @param isMainFrame Whether the navigation is for the main frame.
+     * Called when the browser process starts a navigation.
+     * @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 didStartNavigation(String url, boolean isInMainFrame, boolean isErrorPage) {}
+
+    /**
+     * Called when the current navigation is finished. This happens when a navigation is committed,
+     * aborted or replaced by a new one.
+     * @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).

[Ted C, 2017/01/06 21:50:59]

reduce intent to align with "Whether the " above.

+     * @param isReload Whether the navigation is a reload.
+     * @param errorCode The net error code if an error occurred prior to commit, otherwise net::OK.
      */
-    public void didFinishNavigation(
-            boolean isMainFrame, boolean isErrorPage, boolean hasCommitted) {}
+    public void didFinishNavigation(String url, boolean isInMainFrame, boolean isErrorPage,
+            boolean hasCommitted, boolean isSamePage, boolean isReload, int errorCode) {}

[Ted C, 2017/01/06 21:51:00]

Here if we pass Integer pageTransitionType, I would annotate it with @Nullable.

 
     /**
      * Called when the a page starts loading.
@@ -56,6 +69,7 @@ public abstract class WebContentsObserver {
 
     /**
      * Called when an error occurs while loading a page and/or the page fails to load.
+     * @param isMainFrame Whether the navigation occurred in main frame.
      * @param errorCode Error code for the occurring error.
      * @param description The description for the error.
      * @param failingUrl The url that was loading when the error occurred.