Revert "cc: Make tiling interest rect calc based on viewport."

This reverts commit 6d84db54a27c036d77b0e4a26d42c158ee4a6add.

Reason for revert:
This creates perf regression with top-controls and viewport resizes on
Android (creates and deletes extra tiles).

TBR=vmpstr@chromium.org

BUG=502432

Review URL: https://codereview.chromium.org/1217513002.

Cr-Commit-Position: refs/branch-heads/2403@{#407}
Cr-Branched-From: f54b8097a9c45ed4ad308133d49f05325d6c5070-refs/heads/master@{#330231}

22 files changed, 99 insertions, 49 deletions

diff --git a/cc/base/switches.cc b/cc/base/switches.cc
index c30ab2f..ae42482 100644
--- a/cc/base/switches.cc
+++ b/cc/base/switches.cc
@@ -35,6 +35,9 @@ const char kTopControlsShowThreshold[] = "top-controls-show-threshold";
 // complete, such as --slow-down-raster-scale-factor=25.
 const char kSlowDownRasterScaleFactor[] = "slow-down-raster-scale-factor";
 
+// Max tiles allowed for each tilings interest area.
+const char kMaxTilesForInterestArea[] = "max-tiles-for-interest-area";
+
 // The amount of unused resource memory compositor is allowed to keep around.
 const char kMaxUnusedResourceMemoryUsagePercentage[] =
     "max-unused-resource-memory-usage-percentage";
diff --git a/cc/base/switches.h b/cc/base/switches.h
index 915d8e2..46fe922 100644
--- a/cc/base/switches.h
+++ b/cc/base/switches.h
@@ -25,6 +25,7 @@ CC_EXPORT extern const char kTopControlsHideThreshold[];
 CC_EXPORT extern const char kTopControlsShowThreshold[];
 CC_EXPORT extern const char kSlowDownRasterScaleFactor[];
 CC_EXPORT extern const char kCompositeToMailbox[];
+CC_EXPORT extern const char kMaxTilesForInterestArea[];
 CC_EXPORT extern const char kMaxUnusedResourceMemoryUsagePercentage[];
 CC_EXPORT extern const char kEnablePinchVirtualViewport[];
 CC_EXPORT extern const char kDisablePinchVirtualViewport[];
diff --git a/cc/debug/rasterize_and_record_benchmark_impl.cc b/cc/debug/rasterize_and_record_benchmark_impl.cc
index 22ae8da..1f9a36b8 100644
--- a/cc/debug/rasterize_and_record_benchmark_impl.cc
+++ b/cc/debug/rasterize_and_record_benchmark_impl.cc
@@ -170,8 +170,7 @@ void RasterizeAndRecordBenchmarkImpl::RunOnLayer(PictureLayerImpl* layer) {
   // really matter.
   const LayerTreeSettings& settings = layer->layer_tree_impl()->settings();
   scoped_ptr<PictureLayerTilingSet> tiling_set = PictureLayerTilingSet::Create(
-      layer->GetTree(), &client,
-      settings.tiling_interest_area_viewport_multiplier,
+      layer->GetTree(), &client, settings.max_tiles_for_interest_area,
       settings.skewport_target_time_in_seconds,
       settings.skewport_extrapolation_limit_in_content_pixels);
 
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index 1101440..f9f6d97 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -1147,7 +1147,7 @@ scoped_ptr<PictureLayerTilingSet>
 PictureLayerImpl::CreatePictureLayerTilingSet() {
   const LayerTreeSettings& settings = layer_tree_impl()->settings();
   return PictureLayerTilingSet::Create(
-      GetTree(), this, settings.tiling_interest_area_viewport_multiplier,
+      GetTree(), this, settings.max_tiles_for_interest_area,
       layer_tree_impl()->use_gpu_rasterization()
           ? settings.gpu_rasterization_skewport_target_time_in_seconds
           : settings.skewport_target_time_in_seconds,
diff --git a/cc/layers/picture_layer_impl_perftest.cc b/cc/layers/picture_layer_impl_perftest.cc
index 7c3bbbb..adb0597 100644
--- a/cc/layers/picture_layer_impl_perftest.cc
+++ b/cc/layers/picture_layer_impl_perftest.cc
@@ -41,7 +41,7 @@ class PictureLayerImplPerfTest : public testing::Test {
  public:
   PictureLayerImplPerfTest()
       : proxy_(base::ThreadTaskRunnerHandle::Get()),
-        host_impl_(ImplSidePaintingSettings(10000),
+        host_impl_(ImplSidePaintingSettings(),
                    &proxy_,
                    &shared_bitmap_manager_,
                    &task_graph_runner_),
diff --git a/cc/layers/picture_layer_impl_unittest.cc b/cc/layers/picture_layer_impl_unittest.cc
index 2bf3696..cc89133 100644
--- a/cc/layers/picture_layer_impl_unittest.cc
+++ b/cc/layers/picture_layer_impl_unittest.cc
@@ -2558,8 +2558,8 @@ TEST_F(PictureLayerImplTest, RequiredTilesWithGpuRasterization) {
 
   active_layer_->HighResTiling()->UpdateAllRequiredStateForTesting();
 
-  // High res tiling should have 36 tiles (3X12 tile grid).
-  EXPECT_EQ(36u, active_layer_->HighResTiling()->AllTilesForTesting().size());
+  // High res tiling should have 64 tiles (4x16 tile grid).
+  EXPECT_EQ(64u, active_layer_->HighResTiling()->AllTilesForTesting().size());
 
   // Visible viewport should be covered by 4 tiles.  No other
   // tiles should be required for activation.
diff --git a/cc/test/impl_side_painting_settings.h b/cc/test/impl_side_painting_settings.h
index ede84db..1ea7e78 100644
--- a/cc/test/impl_side_painting_settings.h
+++ b/cc/test/impl_side_painting_settings.h
@@ -15,9 +15,9 @@ class ImplSidePaintingSettings : public LayerTreeSettings {
     impl_side_painting = true;
   }
 
-  explicit ImplSidePaintingSettings(float viewport_multiplier) {
+  explicit ImplSidePaintingSettings(int interest_rect_tiles) {
     impl_side_painting = true;
-    tiling_interest_area_viewport_multiplier = viewport_multiplier;
+    max_tiles_for_interest_area = interest_rect_tiles;
   }
 };
 
diff --git a/cc/tiles/picture_layer_tiling.cc b/cc/tiles/picture_layer_tiling.cc
index 58b048b..c585e55 100644
--- a/cc/tiles/picture_layer_tiling.cc
+++ b/cc/tiles/picture_layer_tiling.cc
@@ -35,12 +35,12 @@ scoped_ptr<PictureLayerTiling> PictureLayerTiling::Create(
     float contents_scale,
     scoped_refptr<RasterSource> raster_source,
     PictureLayerTilingClient* client,
-    float tiling_interest_area_viewport_multiplier,
+    size_t max_tiles_for_interest_area,
     float skewport_target_time_in_seconds,
     int skewport_extrapolation_limit_in_content_pixels) {
   return make_scoped_ptr(new PictureLayerTiling(
-      tree, contents_scale, raster_source, client,
-      tiling_interest_area_viewport_multiplier, skewport_target_time_in_seconds,
+      tree, contents_scale, raster_source, client, max_tiles_for_interest_area,
+      skewport_target_time_in_seconds,
       skewport_extrapolation_limit_in_content_pixels));
 }
 
@@ -49,11 +49,10 @@ PictureLayerTiling::PictureLayerTiling(
     float contents_scale,
     scoped_refptr<RasterSource> raster_source,
     PictureLayerTilingClient* client,
-    float tiling_interest_area_viewport_multiplier,
+    size_t max_tiles_for_interest_area,
     float skewport_target_time_in_seconds,
     int skewport_extrapolation_limit_in_content_pixels)
-    : tiling_interest_area_viewport_multiplier_(
-          tiling_interest_area_viewport_multiplier),
+    : max_tiles_for_interest_area_(max_tiles_for_interest_area),
       skewport_target_time_in_seconds_(skewport_target_time_in_seconds),
       skewport_extrapolation_limit_in_content_pixels_(
           skewport_extrapolation_limit_in_content_pixels),
@@ -573,6 +572,7 @@ bool PictureLayerTiling::ComputeTilePriorityRects(
     DCHECK_NE(current_frame_time_in_seconds, 0.0);
     return false;
   }
+
   gfx::Rect visible_rect_in_content_space =
       gfx::ScaleToEnclosingRect(viewport_in_layer_space, contents_scale_);
 
@@ -589,9 +589,9 @@ bool PictureLayerTiling::ComputeTilePriorityRects(
   DCHECK(skewport.Contains(visible_rect_in_content_space));
 
   // Calculate the eventually/live tiles rect.
-  int64 eventually_rect_area = tiling_interest_area_viewport_multiplier_ *
-                               visible_rect_in_content_space.width() *
-                               visible_rect_in_content_space.height();
+  gfx::Size tile_size = tiling_data_.max_texture_size();
+  int64 eventually_rect_area =
+      max_tiles_for_interest_area_ * tile_size.width() * tile_size.height();
 
   gfx::Rect eventually_rect =
       ExpandRectEquallyToAreaBoundedBy(visible_rect_in_content_space,
diff --git a/cc/tiles/picture_layer_tiling.h b/cc/tiles/picture_layer_tiling.h
index 8af4c4c..33a8187 100644
--- a/cc/tiles/picture_layer_tiling.h
+++ b/cc/tiles/picture_layer_tiling.h
@@ -69,7 +69,7 @@ class CC_EXPORT PictureLayerTiling {
       float contents_scale,
       scoped_refptr<RasterSource> raster_source,
       PictureLayerTilingClient* client,
-      float tiling_interest_area_viewport_multiplier,
+      size_t max_tiles_for_interest_area,
       float skewport_target_time_in_seconds,
       int skewport_extrapolation_limit_in_content_pixels);
 
@@ -237,7 +237,7 @@ class CC_EXPORT PictureLayerTiling {
                      float contents_scale,
                      scoped_refptr<RasterSource> raster_source,
                      PictureLayerTilingClient* client,
-                     float tiling_interest_area_viewport_multiplier,
+                     size_t max_tiles_for_interest_area,
                      float skewport_target_time_in_seconds,
                      int skewport_extrapolation_limit_in_content_pixels);
   void SetLiveTilesRect(const gfx::Rect& live_tiles_rect);
@@ -324,7 +324,7 @@ class CC_EXPORT PictureLayerTiling {
   }
   void RemoveTilesInRegion(const Region& layer_region, bool recreate_tiles);
 
-  const float tiling_interest_area_viewport_multiplier_;
+  const size_t max_tiles_for_interest_area_;
   const float skewport_target_time_in_seconds_;
   const int skewport_extrapolation_limit_in_content_pixels_;
 
diff --git a/cc/tiles/picture_layer_tiling_perftest.cc b/cc/tiles/picture_layer_tiling_perftest.cc
index 3567ecb..0aae512 100644
--- a/cc/tiles/picture_layer_tiling_perftest.cc
+++ b/cc/tiles/picture_layer_tiling_perftest.cc
@@ -52,7 +52,7 @@ class PictureLayerTilingPerfTest : public testing::Test {
             gfx::Size(256 * 50, 256 * 50));
     picture_layer_tiling_ = PictureLayerTiling::Create(
         PENDING_TREE, 1.f, pile, &picture_layer_tiling_client_,
-        defaults.tiling_interest_area_viewport_multiplier,
+        defaults.max_tiles_for_interest_area,
         defaults.skewport_target_time_in_seconds,
         defaults.skewport_extrapolation_limit_in_content_pixels);
     picture_layer_tiling_->CreateAllTilesForTesting();
diff --git a/cc/tiles/picture_layer_tiling_set.cc b/cc/tiles/picture_layer_tiling_set.cc
index 1831539..b794b13 100644
--- a/cc/tiles/picture_layer_tiling_set.cc
+++ b/cc/tiles/picture_layer_tiling_set.cc
@@ -33,11 +33,11 @@ inline float LargerRatio(float float1, float float2) {
 scoped_ptr<PictureLayerTilingSet> PictureLayerTilingSet::Create(
     WhichTree tree,
     PictureLayerTilingClient* client,
-    float tiling_interest_area_viewport_multiplier,
+    size_t max_tiles_for_interest_area,
     float skewport_target_time_in_seconds,
     int skewport_extrapolation_limit_in_content_pixels) {
   return make_scoped_ptr(new PictureLayerTilingSet(
-      tree, client, tiling_interest_area_viewport_multiplier,
+      tree, client, max_tiles_for_interest_area,
       skewport_target_time_in_seconds,
       skewport_extrapolation_limit_in_content_pixels));
 }
@@ -45,11 +45,10 @@ scoped_ptr<PictureLayerTilingSet> PictureLayerTilingSet::Create(
 PictureLayerTilingSet::PictureLayerTilingSet(
     WhichTree tree,
     PictureLayerTilingClient* client,
-    float tiling_interest_area_viewport_multiplier,
+    size_t max_tiles_for_interest_area,
     float skewport_target_time_in_seconds,
     int skewport_extrapolation_limit_in_content_pixels)
-    : tiling_interest_area_viewport_multiplier_(
-          tiling_interest_area_viewport_multiplier),
+    : max_tiles_for_interest_area_(max_tiles_for_interest_area),
       skewport_target_time_in_seconds_(skewport_target_time_in_seconds),
       skewport_extrapolation_limit_in_content_pixels_(
           skewport_extrapolation_limit_in_content_pixels),
@@ -79,8 +78,7 @@ void PictureLayerTilingSet::CopyTilingsAndPropertiesFromPendingTwin(
     if (!this_tiling) {
       scoped_ptr<PictureLayerTiling> new_tiling = PictureLayerTiling::Create(
           tree_, contents_scale, raster_source, client_,
-          tiling_interest_area_viewport_multiplier_,
-          skewport_target_time_in_seconds_,
+          max_tiles_for_interest_area_, skewport_target_time_in_seconds_,
           skewport_extrapolation_limit_in_content_pixels_);
       tilings_.push_back(new_tiling.Pass());
       this_tiling = tilings_.back();
@@ -265,8 +263,7 @@ PictureLayerTiling* PictureLayerTilingSet::AddTiling(
 
   tilings_.push_back(PictureLayerTiling::Create(
       tree_, contents_scale, raster_source, client_,
-      tiling_interest_area_viewport_multiplier_,
-      skewport_target_time_in_seconds_,
+      max_tiles_for_interest_area_, skewport_target_time_in_seconds_,
       skewport_extrapolation_limit_in_content_pixels_));
   PictureLayerTiling* appended = tilings_.back();
 
diff --git a/cc/tiles/picture_layer_tiling_set.h b/cc/tiles/picture_layer_tiling_set.h
index d1367f8..2347d53 100644
--- a/cc/tiles/picture_layer_tiling_set.h
+++ b/cc/tiles/picture_layer_tiling_set.h
@@ -40,7 +40,7 @@ class CC_EXPORT PictureLayerTilingSet {
   static scoped_ptr<PictureLayerTilingSet> Create(
       WhichTree tree,
       PictureLayerTilingClient* client,
-      float tiling_interest_area_viewport_multiplier,
+      size_t max_tiles_for_interest_area,
       float skewport_target_time_in_seconds,
       int skewport_extrapolation_limit_in_content);
 
@@ -176,7 +176,7 @@ class CC_EXPORT PictureLayerTilingSet {
   explicit PictureLayerTilingSet(
       WhichTree tree,
       PictureLayerTilingClient* client,
-      float tiling_interest_area_viewport_multiplier,
+      size_t max_tiles_for_interest_area,
       float skewport_target_time_in_seconds,
       int skewport_extrapolation_limit_in_content_pixels);
 
@@ -191,7 +191,7 @@ class CC_EXPORT PictureLayerTilingSet {
 
   ScopedPtrVector<PictureLayerTiling> tilings_;
 
-  const float tiling_interest_area_viewport_multiplier_;
+  const size_t max_tiles_for_interest_area_;
   const float skewport_target_time_in_seconds_;
   const int skewport_extrapolation_limit_in_content_pixels_;
   WhichTree tree_;
diff --git a/cc/tiles/picture_layer_tiling_set_unittest.cc b/cc/tiles/picture_layer_tiling_set_unittest.cc
index 2d0a1b2..c04870e 100644
--- a/cc/tiles/picture_layer_tiling_set_unittest.cc
+++ b/cc/tiles/picture_layer_tiling_set_unittest.cc
@@ -23,7 +23,7 @@ scoped_ptr<PictureLayerTilingSet> CreateTilingSet(
     PictureLayerTilingClient* client) {
   LayerTreeSettings defaults;
   return PictureLayerTilingSet::Create(
-      ACTIVE_TREE, client, defaults.tiling_interest_area_viewport_multiplier,
+      ACTIVE_TREE, client, defaults.max_tiles_for_interest_area,
       defaults.skewport_target_time_in_seconds,
       defaults.skewport_extrapolation_limit_in_content_pixels);
 }
diff --git a/cc/tiles/picture_layer_tiling_unittest.cc b/cc/tiles/picture_layer_tiling_unittest.cc
index 31caf46..e19f930 100644
--- a/cc/tiles/picture_layer_tiling_unittest.cc
+++ b/cc/tiles/picture_layer_tiling_unittest.cc
@@ -48,7 +48,7 @@ class TestablePictureLayerTiling : public PictureLayerTiling {
       const LayerTreeSettings& settings) {
     return make_scoped_ptr(new TestablePictureLayerTiling(
         tree, contents_scale, raster_source, client,
-        settings.tiling_interest_area_viewport_multiplier,
+        settings.max_tiles_for_interest_area,
         settings.skewport_target_time_in_seconds,
         settings.skewport_extrapolation_limit_in_content_pixels));
   }
@@ -63,14 +63,14 @@ class TestablePictureLayerTiling : public PictureLayerTiling {
                              float contents_scale,
                              scoped_refptr<RasterSource> raster_source,
                              PictureLayerTilingClient* client,
-                             float tiling_interest_area_viewport_multiplier,
+                             size_t max_tiles_for_interest_area,
                              float skewport_target_time,
                              int skewport_extrapolation_limit)
       : PictureLayerTiling(tree,
                            contents_scale,
                            raster_source,
                            client,
-                           tiling_interest_area_viewport_multiplier,
+                           max_tiles_for_interest_area,
                            skewport_target_time,
                            skewport_extrapolation_limit) {}
 };
@@ -549,6 +549,7 @@ TEST(PictureLayerTilingTest, SkewportLimits) {
 
   client.SetTileSize(gfx::Size(100, 100));
   LayerTreeSettings settings;
+  settings.max_tiles_for_interest_area = 10000;
   settings.skewport_extrapolation_limit_in_content_pixels = 75;
 
   scoped_refptr<FakePicturePileImpl> pile =
@@ -791,7 +792,7 @@ TEST(PictureLayerTilingTest, ViewportDistanceWithScale) {
 
   client.SetTileSize(gfx::Size(10, 10));
   LayerTreeSettings settings;
-  settings.tiling_interest_area_viewport_multiplier = 10000;
+  settings.max_tiles_for_interest_area = 10000;
 
   // Tiling at 0.25 scale: this should create 47x47 tiles of size 10x10.
   // The reason is that each tile has a one pixel border, so tile at (1, 2)
@@ -1291,7 +1292,7 @@ TEST_F(PictureLayerTilingIteratorTest,
   gfx::Size layer_bounds(10000, 10000);
   client_.SetTileSize(gfx::Size(100, 100));
   LayerTreeSettings settings;
-  settings.tiling_interest_area_viewport_multiplier = 1;
+  settings.max_tiles_for_interest_area = 1;
 
   scoped_refptr<FakePicturePileImpl> pile =
       FakePicturePileImpl::CreateFilledPileWithDefaultTileSize(layer_bounds);
@@ -1748,7 +1749,7 @@ TEST(ComputeTilePriorityRectsTest, BasicMotion) {
 
   client.SetTileSize(gfx::Size(100, 100));
   LayerTreeSettings settings;
-  settings.tiling_interest_area_viewport_multiplier = 10000;
+  settings.max_tiles_for_interest_area = 10000;
 
   scoped_refptr<FakePicturePileImpl> pile =
       FakePicturePileImpl::CreateFilledPileWithDefaultTileSize(
@@ -1878,6 +1879,7 @@ TEST(PictureLayerTilingTest, RecycledTilesCleared) {
 
   active_client.SetTileSize(gfx::Size(100, 100));
   LayerTreeSettings settings;
+  settings.max_tiles_for_interest_area = 10;
 
   scoped_refptr<FakePicturePileImpl> pile =
       FakePicturePileImpl::CreateFilledPileWithDefaultTileSize(
@@ -1945,6 +1947,7 @@ TEST(PictureLayerTilingTest, RecycledTilesClearedOnReset) {
   recycle_client.set_twin_tiling(active_tiling.get());
 
   LayerTreeSettings settings;
+  settings.max_tiles_for_interest_area = 10;
 
   pile = FakePicturePileImpl::CreateFilledPileWithDefaultTileSize(
       gfx::Size(100, 100));
diff --git a/cc/tiles/tile_manager_unittest.cc b/cc/tiles/tile_manager_unittest.cc
index 5c7e3c1..bddf29f 100644
--- a/cc/tiles/tile_manager_unittest.cc
+++ b/cc/tiles/tile_manager_unittest.cc
@@ -30,10 +30,7 @@ namespace {
 
 class LowResTilingsSettings : public ImplSidePaintingSettings {
  public:
-  LowResTilingsSettings() {
-    tiling_interest_area_viewport_multiplier = 10000;
-    create_low_res_tiling = true;
-  }
+  LowResTilingsSettings() { create_low_res_tiling = true; }
 };
 
 class TileManagerTilePriorityQueueTest : public testing::Test {
@@ -1180,10 +1177,10 @@ TEST_F(TileManagerTilePriorityQueueTest,
 
   client.SetTileSize(gfx::Size(30, 30));
   LayerTreeSettings settings;
-  settings.tiling_interest_area_viewport_multiplier = 10000;
+  settings.max_tiles_for_interest_area = 10000;
 
   scoped_ptr<PictureLayerTilingSet> tiling_set = PictureLayerTilingSet::Create(
-      ACTIVE_TREE, &client, settings.tiling_interest_area_viewport_multiplier,
+      ACTIVE_TREE, &client, settings.max_tiles_for_interest_area,
       settings.skewport_target_time_in_seconds,
       settings.skewport_extrapolation_limit_in_content_pixels);
 
@@ -1290,9 +1287,10 @@ TEST_F(TileManagerTilePriorityQueueTest,
 
   client.SetTileSize(gfx::Size(30, 30));
   LayerTreeSettings settings;
+  settings.max_tiles_for_interest_area = 10000;
 
   scoped_ptr<PictureLayerTilingSet> tiling_set = PictureLayerTilingSet::Create(
-      ACTIVE_TREE, &client, settings.tiling_interest_area_viewport_multiplier,
+      ACTIVE_TREE, &client, settings.max_tiles_for_interest_area,
       settings.skewport_target_time_in_seconds,
       settings.skewport_extrapolation_limit_in_content_pixels);
 
diff --git a/cc/trees/layer_tree_settings.cc b/cc/trees/layer_tree_settings.cc
index d2c3bda..f7f6f30 100644
--- a/cc/trees/layer_tree_settings.cc
+++ b/cc/trees/layer_tree_settings.cc
@@ -52,7 +52,8 @@ LayerTreeSettings::LayerTreeSettings()
       default_tile_grid_size(gfx::Size(256, 256)),
       minimum_occlusion_tracking_size(gfx::Size(160, 160)),
       use_pinch_virtual_viewport(false),
-      tiling_interest_area_viewport_multiplier(9.0f),
+      // At 256x256 tiles, 128 tiles cover an area of 2048x4096 pixels.
+      max_tiles_for_interest_area(128),
       skewport_target_time_in_seconds(1.0f),
       skewport_extrapolation_limit_in_content_pixels(2000),
       max_unused_resource_memory_percentage(100),
diff --git a/cc/trees/layer_tree_settings.h b/cc/trees/layer_tree_settings.h
index 0e1819b..56cfa3a 100644
--- a/cc/trees/layer_tree_settings.h
+++ b/cc/trees/layer_tree_settings.h
@@ -65,7 +65,7 @@ class CC_EXPORT LayerTreeSettings {
   gfx::Size default_tile_grid_size;
   gfx::Size minimum_occlusion_tracking_size;
   bool use_pinch_virtual_viewport;
-  float tiling_interest_area_viewport_multiplier;
+  size_t max_tiles_for_interest_area;
   float skewport_target_time_in_seconds;
   int skewport_extrapolation_limit_in_content_pixels;
   size_t max_unused_resource_memory_percentage;
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index f4bfef8..8fb481c 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -6540,6 +6540,24 @@ Keep your key file in a safe place. You will need it to create new versions of y
       <message name="IDS_FLAGS_ZERO_COPY_DESCRIPTION" desc="Description of about:flags option for zero-copy rasterizer.">
         If enabled, raster threads write directly to GPU memory associated with tiles.
       </message>
+      <message name="IDS_FLAGS_MAX_TILES_FOR_INTEREST_AREA_NAME" desc="Name of about:flags option for maximum tiles for interest area.">
+        Maximum tiles for interest area
+      </message>
+      <message name="IDS_FLAGS_MAX_TILES_FOR_INTEREST_AREA_DESCRIPTION" desc="Description of about:flags option for maximum tiles for interest area.">
+        Specify the maximum tiles for interest area.
+      </message>
+      <message name="IDS_FLAGS_MAX_TILES_FOR_INTEREST_AREA_SHORT" desc="">
+        64
+      </message>
+      <message name="IDS_FLAGS_MAX_TILES_FOR_INTEREST_AREA_TALL" desc="">
+        128
+      </message>
+      <message name="IDS_FLAGS_MAX_TILES_FOR_INTEREST_AREA_GRANDE" desc="">
+        256
+      </message>
+      <message name="IDS_FLAGS_MAX_TILES_FOR_INTEREST_AREA_VENTI" desc="">
+        512
+      </message>
       <message name="IDS_FLAGS_TAB_CAPTURE_UPSCALE_QUALITY_NAME" desc="">
         Tab capture upscaling quality.
       </message>
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index b90ed85..6f42c9c 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -215,6 +215,18 @@ const Experiment::Choice kMarkNonSecureAsChoices[] = {
         switches::kMarkNonSecureAs, switches::kMarkNonSecureAsDubious}
 };
 
+const Experiment::Choice kMaxTilesForInterestAreaChoices[] = {
+  { IDS_GENERIC_EXPERIMENT_CHOICE_DEFAULT, "", "" },
+  { IDS_FLAGS_MAX_TILES_FOR_INTEREST_AREA_SHORT,
+    cc::switches::kMaxTilesForInterestArea, "64"},
+  { IDS_FLAGS_MAX_TILES_FOR_INTEREST_AREA_TALL,
+    cc::switches::kMaxTilesForInterestArea, "128"},
+  { IDS_FLAGS_MAX_TILES_FOR_INTEREST_AREA_GRANDE,
+    cc::switches::kMaxTilesForInterestArea, "256"},
+  { IDS_FLAGS_MAX_TILES_FOR_INTEREST_AREA_VENTI,
+    cc::switches::kMaxTilesForInterestArea, "512"}
+};
+
 const Experiment::Choice kShowSavedCopyChoices[] = {
   { IDS_GENERIC_EXPERIMENT_CHOICE_DEFAULT, "", "" },
   { IDS_FLAGS_ENABLE_SHOW_SAVED_COPY_PRIMARY,
@@ -1294,6 +1306,13 @@ const Experiment kExperiments[] = {
   },
 #endif
   {
+    "max-tiles-for-interest-area",
+    IDS_FLAGS_MAX_TILES_FOR_INTEREST_AREA_NAME,
+    IDS_FLAGS_MAX_TILES_FOR_INTEREST_AREA_DESCRIPTION,
+    kOsAll,
+    MULTI_VALUE_TYPE(kMaxTilesForInterestAreaChoices)
+  },
+  {
     "enable-offer-store-unmasked-wallet-cards",
     IDS_FLAGS_ENABLE_OFFER_STORE_UNMASKED_WALLET_CARDS,
     IDS_FLAGS_ENABLE_OFFER_STORE_UNMASKED_WALLET_CARDS_DESCRIPTION,
diff --git a/chrome/browser/chromeos/login/chrome_restart_request.cc b/chrome/browser/chromeos/login/chrome_restart_request.cc
index 3ef1d9c..9108984 100644
--- a/chrome/browser/chromeos/login/chrome_restart_request.cc
+++ b/chrome/browser/chromeos/login/chrome_restart_request.cc
@@ -190,6 +190,7 @@ std::string DeriveCommandLine(const GURL& start_url,
     cc::switches::kEnablePinchVirtualViewport,
     cc::switches::kEnablePropertyTreeVerification,
     cc::switches::kEnableMainFrameBeforeActivation,
+    cc::switches::kMaxTilesForInterestArea,
     cc::switches::kMaxUnusedResourceMemoryUsagePercentage,
     cc::switches::kShowCompositedLayerBorders,
     cc::switches::kShowFPSCounter,
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index f0f1996..00f3414 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -1333,6 +1333,7 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
     cc::switches::kDisableThreadedAnimation,
     cc::switches::kEnableGpuBenchmarking,
     cc::switches::kEnableMainFrameBeforeActivation,
+    cc::switches::kMaxTilesForInterestArea,
     cc::switches::kMaxUnusedResourceMemoryUsagePercentage,
     cc::switches::kShowCompositedLayerBorders,
     cc::switches::kShowFPSCounter,
diff --git a/content/renderer/gpu/render_widget_compositor.cc b/content/renderer/gpu/render_widget_compositor.cc
index c8400037..8f4cccc6 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -350,6 +350,15 @@ void RenderWidgetCompositor::Initialize() {
         &settings.initial_debug_state.slow_down_raster_scale_factor);
   }
 
+  if (cmd->HasSwitch(cc::switches::kMaxTilesForInterestArea)) {
+    int max_tiles_for_interest_area;
+    if (GetSwitchValueAsInt(*cmd,
+                            cc::switches::kMaxTilesForInterestArea,
+                            1, std::numeric_limits<int>::max(),
+                            &max_tiles_for_interest_area))
+      settings.max_tiles_for_interest_area = max_tiles_for_interest_area;
+  }
+
   if (cmd->HasSwitch(cc::switches::kMaxUnusedResourceMemoryUsagePercentage)) {
     int max_unused_resource_memory_percentage;
     if (GetSwitchValueAsInt(