Revert "Revert "Clear the bitmap associated with canvases.""

This reverts commit 4e012846cd.

src/com/android/launcher2/Workspace.java

@@ -1985,6 +1985,7 @@ public class Workspace extends SmoothPagedView
         canvas.setBitmap(b);
         drawDragView(v, canvas, padding, true);
         mOutlineHelper.applyOuterBlur(b, canvas, outlineColor);
+        canvas.setBitmap(null);
 
         return b;
     }
@@ -2001,6 +2002,7 @@ public class Workspace extends SmoothPagedView
         canvas.setBitmap(b);
         drawDragView(v, canvas, padding, false);
         mOutlineHelper.applyMediumExpensiveOutlineWithBlur(b, canvas, outlineColor, outlineColor);
+        canvas.setBitmap(null);
         return b;
     }
 
@@ -2027,6 +2029,7 @@ public class Workspace extends SmoothPagedView
         p.setFilterBitmap(true);
         canvas.drawBitmap(orig, src, dst, p);
         mOutlineHelper.applyMediumExpensiveOutlineWithBlur(b, canvas, outlineColor, outlineColor);
+        canvas.setBitmap(null);
 
         return b;
     }
@@ -2050,6 +2053,7 @@ public class Workspace extends SmoothPagedView
         canvas.drawRoundRect(new RectF(inset, inset, iconWidth - inset, iconHeight - inset),
                 rectRadius, rectRadius, mExternalDragOutlinePaint);
         mOutlineHelper.applyMediumExpensiveOutlineWithBlur(b, canvas, outlineColor, outlineColor);
+        canvas.setBitmap(null);
         return b;
     }