Fixing tile grid size used by cc:Picture to make it respect current tile configuration

cc/picture_pile_base.cc

Index: cc/picture_pile_base.cc
diff --git a/cc/picture_pile_base.cc b/cc/picture_pile_base.cc
index 94983847afcc63ff943c57bb82b547c3a160243e..50f7f6e3ff7c48285635fea8da2b8cf200abf273 100644
--- a/cc/picture_pile_base.cc
+++ b/cc/picture_pile_base.cc
@@ -10,6 +10,8 @@ namespace {
 // Dimensions of the tiles in this picture pile as well as the dimensions of
 // the base picture in each tile.
 const int kBasePictureSize = 3000;
+const int kDefaultTileGridSize = 256;
+const int kDefaultTileGridBorderPixels = 1;
 }
 
 namespace cc {
@@ -17,6 +19,8 @@ namespace cc {
 PicturePileBase::PicturePileBase()
     : min_contents_scale_(0) {
   tiling_.SetMaxTextureSize(gfx::Size(kBasePictureSize, kBasePictureSize));
+  SetTileGridSize(gfx::Size(kDefaultTileGridSize, kDefaultTileGridSize),
+      kDefaultTileGridBorderPixels);
 }
 
 PicturePileBase::~PicturePileBase() {
@@ -67,6 +71,18 @@ void PicturePileBase::SetMinContentsScale(float min_contents_scale) {
   min_contents_scale_ = min_contents_scale;
 }
 
+void PicturePileBase::SetTileGridSize(gfx::Size tile_size, int borderPixels) {
+    DCHECK(tile_size.width() - 2 * borderPixels > 0);
+    DCHECK(tile_size.height() - 2 * borderPixels > 0);
+    tile_grid_info_.fTileInterval.set(tile_size.width() - 2 * borderPixels,
+        tile_size.height() - 2 * borderPixels);
+    tile_grid_info_.fMargin.set(borderPixels, borderPixels);
+    // Offset the tile grid coordinate space to take into account the fact
+    // that the top-most and left-most tiles do not have top and left borders
+    // respectively. This offset 
+    tile_grid_info_.fOffset.set(-borderPixels, -borderPixels);
+}
+
 void PicturePileBase::SetBufferPixels(int new_buffer_pixels) {
   if (new_buffer_pixels == buffer_pixels())
     return;
@@ -84,6 +100,7 @@ void PicturePileBase::PushPropertiesTo(PicturePileBase* other) {
   other->tiling_ = tiling_;
   other->recorded_region_ = recorded_region_;
   other->min_contents_scale_ = min_contents_scale_;
+  other->tile_grid_info_ = tile_grid_info_;
 }
 
 void PicturePileBase::UpdateRecordedRegion() {