cc: Changed ComputeExpansionDelta to never return a delta less than zero

cc/resources/picture_layer_tiling_unittest.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/resources/picture_layer_tiling.h"
 
 #include <limits>
 #include <set>
 
 #include "cc/base/math_util.h"
@@ skipping 851 matching lines @@
 
 TEST(PictureLayerTilingTest, ExpandRectSmaller) {
   gfx::Rect in(40, 50, 100, 200);
   gfx::Rect bounds(-1000, -1000, 10000, 10000);
   int64 target_area = 100 * 100;
   gfx::Rect out = PictureLayerTiling::ExpandRectEquallyToAreaBoundedBy(
       in, target_area, bounds, NULL);
   EXPECT_EQ(out.bottom() - in.bottom(), in.y() - out.y());
   EXPECT_EQ(out.right() - in.right(), in.x() - out.x());
   EXPECT_EQ(out.width() - in.width(), out.height() - in.height());
-  EXPECT_NEAR(100 * 100, out.width() * out.height(), 50);
+
+  // |in| represents the visible rect, and |out| represents the eventually rect.
+  // If the eventually rect doesn't contain the visible rect, we will start
+  // losing tiles.
+  EXPECT_TRUE(out.Contains(in));
   EXPECT_TRUE(bounds.Contains(out));
 }
 
 TEST(PictureLayerTilingTest, ExpandRectUnbounded) {
   gfx::Rect in(40, 50, 100, 200);
   gfx::Rect bounds(-1000, -1000, 10000, 10000);
   int64 target_area = 200 * 200;
   gfx::Rect out = PictureLayerTiling::ExpandRectEquallyToAreaBoundedBy(
       in, target_area, bounds, NULL);
   EXPECT_EQ(out.bottom() - in.bottom(), in.y() - out.y());
@@ skipping 559 matching lines @@
                                 1.f,                // current contents scale
                                 1.0,                // current frame time
                                 NULL,               // occlusion tracker
                                 NULL,               // render target
                                 gfx::Transform());  // draw transform
   VerifyTiles(1.f,
               gfx::Rect(layer_bounds),
               base::Bind(&TilesIntersectingRectExist, visible_rect, true));
 }
 
-static void CountExistingTiles(int *count,
-                               Tile* tile,
-                               const gfx::Rect& geometry_rect) {
-  if (tile != NULL)
-    ++(*count);
-}
-
-TEST_F(PictureLayerTilingIteratorTest,
-       TilesExistLargeViewportAndLayerWithLargeVisibleArea) {
-  gfx::Size layer_bounds(10000, 10000);
-  Initialize(gfx::Size(100, 100), 1.f, layer_bounds);
-  VerifyTilesExactlyCoverRect(1.f, gfx::Rect(layer_bounds));
-  VerifyTiles(1.f, gfx::Rect(layer_bounds), base::Bind(&TileExists, false));
-
-  client_.set_tree(ACTIVE_TREE);
-  set_max_tiles_for_interest_area(1);
-  tiling_->UpdateTilePriorities(
-      ACTIVE_TREE,
-      gfx::Rect(layer_bounds),  // visible content rect
-      1.f,                      // current contents scale
-      1.0,                      // current frame time
-      NULL,                     // occlusion tracker
-      NULL,                     // render target
-      gfx::Transform());        // draw transform
-
-  int num_tiles = 0;
-  VerifyTiles(1.f,
-              gfx::Rect(layer_bounds),
-              base::Bind(&CountExistingTiles, &num_tiles));
-  // If we're making a rect the size of one tile, it can only overlap up to 4
-  // tiles depending on its position.
-  EXPECT_LE(num_tiles, 4);
-  VerifyTiles(1.f, gfx::Rect(), base::Bind(&TileExists, false));
-}
-
 TEST_F(PictureLayerTilingIteratorTest, AddTilingsToMatchScale) {
   gfx::Size layer_bounds(1099, 801);
   gfx::Size tile_size(100, 100);
 
   client_.SetTileSize(tile_size);
   client_.set_tree(PENDING_TREE);
 
   PictureLayerTilingSet active_set(&client_, layer_bounds);
 
   active_set.AddTiling(1.f);
@@ skipping 779 matching lines @@
   EXPECT_EQ(active_tiling->TileAt(0, 0), recycle_tiling->TileAt(0, 0));
 
   // Reset the active tiling. The recycle tiles should be released too.
   active_tiling->Reset();
   EXPECT_FALSE(active_tiling->TileAt(0, 0));
   EXPECT_FALSE(recycle_tiling->TileAt(0, 0));
 }
 
 }  // namespace
 }  // namespace cc