viz: Pass device_scale_factor as a float to CanSplitQuad

|device_scale_factor_| is a float and was incorrectly passed as an int
to CanSplitQuad.
This would cause rounding down the device scale factor and incorrectly
computing the number of fragments we are saving.

Bug: 1022544
Test: viz_unittests --gtest_filter="*DrawOcclusionSplitDeviceScaleFactor*"

Change-Id: I084cb9ce52116b0d37e18ff74dd06233978cb9a0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2072625
Commit-Queue: Daniele Castagna <dcastagna@chromium.org>
Reviewed-by: Andres Calderon Jaramillo <andrescj@chromium.org>
Reviewed-by: Gil Dekel <gildekel@chromium.org>
Reviewed-by: Sasha McIntosh <sashamcintosh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745520}

components/viz/service/display/display.cc

@@ -170,7 +170,7 @@ bool CanSplitQuad(const DrawQuad::Material m,
                   const cc::Region& visible_region,
                   const int quad_split_limit,
                   const int minimum_fragments_reduced,
-                  const int device_scale_factor,
+                  const float device_scale_factor,
                   const bool enable_quad_splitting) {
   return enable_quad_splitting && !base::Contains(kNonSplittableMaterials, m) &&
          visible_region.GetRegionComplexity() < quad_split_limit &&

components/viz/service/display/display_unittest.cc

@@ -12,7 +12,6 @@
 #include "base/test/metrics/histogram_tester.h"
 #include "base/test/null_task_runner.h"
 #include "cc/base/math_util.h"
-#include "cc/base/region.h"
 #include "cc/test/scheduler_test_common.h"
 #include "components/viz/common/frame_sinks/begin_frame_source.h"
 #include "components/viz/common/frame_sinks/copy_output_request.h"
@@ -4210,6 +4209,61 @@ TEST_F(DisplayTest, DrawOcclusionSplit) {
   TearDownDisplay();
 }
 
+// Test that the threshold we use to determine if it's worth splitting a quad or
+// not takes into account the device scale factor. In particular, this test
+// would not pass if we had a display scale factor equal to 1.f instead of 1.5f
+// since the number of saved fragments would only be 100x100 which is lower than
+// our threshold 128x128.
+TEST_F(DisplayTest, DrawOcclusionSplitDeviceScaleFactorFractional) {
+  SetUpGpuDisplay(RendererSettings());
+
+  StubDisplayClient client;
+  display_->Initialize(&client, manager_.surface_manager());
+  display_->SetLocalSurfaceId(
+      id_allocator_.GetCurrentLocalSurfaceIdAllocation().local_surface_id(),
+      1.5f);
+  display_->Resize(gfx::Size(1000, 1000));
+
+  CompositorFrame frame = MakeDefaultCompositorFrame();
+
+  const bool is_clipped = false;
+  const bool are_contents_opaque = true;
+  const float opacity = 1.f;
+
+  // Occluder quad.
+  const gfx::Rect occluding_rect(10, 10, 100, 100);
+  SharedQuadState* shared_quad_state_occluding =
+      frame.render_pass_list.front()->CreateAndAppendSharedQuadState();
+  SolidColorDrawQuad* occluding_quad =
+      frame.render_pass_list.front()
+          ->quad_list.AllocateAndConstruct<SolidColorDrawQuad>();
+  shared_quad_state_occluding->SetAll(
+      gfx::Transform(), occluding_rect, occluding_rect, gfx::RRectF(),
+      occluding_rect, is_clipped, are_contents_opaque, opacity,
+      SkBlendMode::kSrcOver, 0);
+  occluding_quad->SetNew(shared_quad_state_occluding, occluding_rect,
+                         occluding_rect, SK_ColorRED, false);
+  // Occluded quad.
+  const gfx::Rect occluded_rect = gfx::Rect(0, 0, 1000, 1000);
+  SharedQuadState* shared_quad_state_occluded =
+      frame.render_pass_list.front()->CreateAndAppendSharedQuadState();
+  SolidColorDrawQuad* occluded_quad =
+      frame.render_pass_list.front()
+          ->quad_list.AllocateAndConstruct<SolidColorDrawQuad>();
+  shared_quad_state_occluded->SetAll(
+      gfx::Transform(), occluded_rect, occluded_rect, gfx::RRectF(),
+      occluded_rect, is_clipped, are_contents_opaque, opacity,
+      SkBlendMode::kSrcOver, 0);
+  occluded_quad->SetNew(shared_quad_state_occluded, occluded_rect,
+                        occluded_rect, SK_ColorRED, false);
+
+  EXPECT_EQ(2u, frame.render_pass_list.front()->quad_list.size());
+  display_->RemoveOverdrawQuads(&frame);
+  EXPECT_EQ(5u, frame.render_pass_list.front()->quad_list.size());
+
+  TearDownDisplay();
+}
+
 TEST_F(DisplayTest, DrawOcclusionWithRoundedCornerPartialOcclude) {
   SetUpGpuDisplay(RendererSettings());