Don't scroll the title bar off screen while loading.

Though the user can still manually scroll the title bar
off screen, we do not want it to happen automatically.
When we load a new page, its scroll position can be
set to (0,0).  Make sure that we simply set it to the
top without adding in the title bar's height.  Also,
prevent javascript which attempts to scroll the page
to (0,0) or (0,1) from removing the title bar.

Fixes http://b/issue?id=2113398 and http://b/issue?id=2123079

Change-Id: Ida64d8c94be6744c7b0b4d60af1c229b2cc83673

1 files changed, 16 insertions, 12 deletions

diff --git a/core/java/android/webkit/WebView.java b/core/java/android/webkit/WebView.java
index 740c39e003ad..12eb93498091 100644
--- a/core/java/android/webkit/WebView.java
+++ b/core/java/android/webkit/WebView.java
@@ -420,7 +420,6 @@ public class WebView extends AbsoluteLayout
     private static final int STD_SPEED = 480;  // pixels per second
     // time for the longest scroll animation
     private static final int MAX_DURATION = 750;   // milliseconds
-    private static final int SLIDE_TITLE_DURATION = 300;   // milliseconds
     private Scroller mScroller;
 
     private boolean mWrapContent;
@@ -2418,18 +2417,17 @@ public class WebView extends AbsoluteLayout
         if ((dx | dy) == 0) {
             return false;
         }
+        // By this point we have added in the title bar's height.  If the site
+        // is trying to scroll to the top of the page, scroll it to the top
+        // of the WebView including showing the title bar.
         // mobile sites prefer to scroll to (0, 1), thus the + 1 below
-        boolean slideTitle = getVisibleTitleHeight() > 0
-            && y <= getTitleHeight() + 1;
-        if (DebugFlags.WEB_VIEW) {
-            Log.v(LOGTAG, "pinScrollTo slideTitle=" + slideTitle
-                    + " getVisibleTitleHeight()=" + getVisibleTitleHeight()
-                    + " animationDuration=" + animationDuration + " y=" + y);
+        if (getVisibleTitleHeight() > 0 && x == 0
+                && y <= getTitleHeight() + 1) {
+            y = 0;
+            animate = false;
         }
-        if (slideTitle || animate) {
+        if (animate) {
             //        Log.d(LOGTAG, "startScroll: " + dx + " " + dy);
-            if (slideTitle && animationDuration < SLIDE_TITLE_DURATION)
-                animationDuration = SLIDE_TITLE_DURATION;
             mScroller.startScroll(mScrollX, mScrollY, dx, dy,
                     animationDuration > 0 ? animationDuration : computeDuration(dx, dy));
             invalidate();
@@ -4809,8 +4807,14 @@ public class WebView extends AbsoluteLayout
                             mMaxZoomScale = restoreState.mMaxScale;
                         }
                         setNewZoomScale(mLastScale, false);
-                        if (getVisibleTitleHeight() == 0
-                                || restoreState.mScrollY != 0) {
+                        if (getTitleHeight() != 0 && restoreState.mScrollX == 0
+                                && restoreState.mScrollY == 0) {
+                            // If there is a title bar, and the page is being
+                            // restored to (0,0), do not scroll the title bar
+                            // off the page.
+                            abortAnimation();
+                            scrollTo(0,0);
+                        } else {
                             setContentScrollTo(restoreState.mScrollX,
                                     restoreState.mScrollY);
                         }