Adds metric to help assess last_n impact on tab restores.

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 da0941dab8e8cd358b35cc5d4304800486da6fe9..0a431e16de79baf934ec228d70daa58144e3198f 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
@@ -455,7 +455,7 @@ public class Tab
 
             if (didFinishLoad) {
                 // Simulate the PAGE_LOAD_FINISHED notification that we did not get.
-                didFinishPageLoad();
+                didFinishPageLoad(url);
             }
         }
     };
@@ -1524,8 +1524,11 @@ public class Tab
     /**
      * Called when a page has finished loading.
      */
-    protected void didFinishPageLoad() {
-        mIsBeingRestored = false;
+    protected void didFinishPageLoad(String validatedUrl) {

[Dmitry Titov, 2017/03/17 01:39:51]

You probalby can just tab.getURL() instead of passing a url...

[carlosk, 2017/03/17 20:37:22]

Done.

+        if (mIsBeingRestored) {
+            OfflinePageUtils.finishedRestorePageLoad(this, validatedUrl);
+            mIsBeingRestored = false;
+        }
         mIsTabStateDirty = true;
         updateTitle();
         updateFullscreenEnabledState();
@@ -1547,7 +1550,10 @@ public class Tab
      * @param errorCode The error code causing the page to fail loading.
      */
     protected void didFailPageLoad(int errorCode) {
-        mIsBeingRestored = false;
+        if (mIsBeingRestored) {
+            OfflinePageUtils.failedRestorePageLoad(errorCode);
+            mIsBeingRestored = false;
+        }
         if (mTabUma != null) mTabUma.onLoadFailed(errorCode);
         for (TabObserver observer : mObservers) observer.onPageLoadFailed(this, errorCode);
     }
@@ -2546,7 +2552,10 @@ public class Tab
      */
     void handleTabCrash() {
         mIsLoading = false;
-        mIsBeingRestored = false;
+        if (mIsBeingRestored) {
+            OfflinePageUtils.crashedWhileRestoringPageLoad();
+            mIsBeingRestored = false;
+        }
 
         if (mTabUma != null) mTabUma.onRendererCrashed();
     }