Prevent the usage of the texture(tile) if considered un-usable

As an example of gmail, even though clearView is called, the previous
content still show up.
This fix just use a usable flag to make sure the content
in the previously used texture is not showing up.

bug : 3215000

Change-Id: I5429a4d03547d4cd4ad10bd2153c247a4d40db7d

1 files changed, 3 insertions, 1 deletions

diff --git a/WebCore/platform/graphics/android/BaseTile.h b/WebCore/platform/graphics/android/BaseTile.h
index 8f095e3..22e85d1 100644
--- a/WebCore/platform/graphics/android/BaseTile.h
+++ b/WebCore/platform/graphics/android/BaseTile.h
@@ -81,7 +81,7 @@ public:
 
     void markAsDirty(const unsigned int pictureCount);
     bool isDirty();
-
+    void setUsable(bool usable);
     float scale() const { return m_scale; }
     void setScale(float scale);
 
@@ -101,6 +101,8 @@ private:
     float m_scale;
     // used to signal that the that the tile is out-of-date and needs to be redrawn
     bool m_dirty;
+    // used to signal whether or not the draw can use this tile.
+    bool m_usable;
     // stores the id of the latest picture from webkit that caused this tile to
     // become dirty. A tile is no longer dirty when it has been painted with a
     // picture that is newer than this value.