Revert "Skip promoting SingleOnTop Overlay when contents don't change"

This reverts commit b4fd0cc9.

Reason for revert: The Squid app uses SingleOnTop for overlay without changing the resource_id. This revert will undo the fix for the other apps, but they're lower priority.

Original change's description:
> Skip promoting SingleOnTop Overlay when contents don't change
>
> If a candidate content has not changed for 3 frames, do not promote it as
> Single On Top overlay as it can be just be flattened, allowing other
> strategies to kick in if possible.
>
> Bug: 885180
> Test: SingleOverlayOnTopTest.DoNotPromoteIfPreviouslyPromoted
> Change-Id: I516dab628c129fe9fae09c713e2783a6ce889c56
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1521591
> Commit-Queue: Mark Yacoub <markyacoub@google.com>
> Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#645367}

TBR=dcastagna@chromium.org,markyacoub@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 885180
Change-Id: I799bd22f06a56d86844a63d5ac346f41bcfb8707
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1635931Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Commit-Queue: Mark Yacoub <markyacoub@google.com>
Cr-Commit-Position: refs/heads/master@{#664734}

components/viz/service/display/overlay_strategy_single_on_top.cc

@@ -35,15 +35,6 @@ bool OverlayStrategySingleOnTop::Attempt(
     if (OverlayCandidate::FromDrawQuad(resource_provider, output_color_matrix,
                                        *it, &candidate) &&
         !OverlayCandidate::IsOccluded(candidate, quad_list->cbegin(), it)) {
-      // If the candidate has been promoted previously and has not changed
-      // (resource ID is the same) for 3 frames, do not use it as Overlay as
-      // flattening it to the main fb will be more power efficient when the
-      // contents don't change.
-      if (candidate.resource_id == previous_frame_resource_id_ &&
-          ++same_resource_id_frames_count_ >
-              kMaxFrameCandidateWithSameResourceId) {
-        continue;
-      }
       if (candidate.display_rect.size().GetArea() >
           best_candidate.display_rect.size().GetArea()) {
         best_candidate = candidate;
@@ -54,17 +45,10 @@ bool OverlayStrategySingleOnTop::Attempt(
   if (best_quad_it == quad_list->end())
     return false;
 
-  if (TryOverlay(quad_list, candidate_list, best_candidate, best_quad_it)) {
-    if (previous_frame_resource_id_ != best_candidate.resource_id) {
-      previous_frame_resource_id_ = best_candidate.resource_id;
-      same_resource_id_frames_count_ = 1;
-    }
+  if (TryOverlay(quad_list, candidate_list, best_candidate, best_quad_it))
     return true;
-  } else {
-    previous_frame_resource_id_ = kInvalidResourceId;
-    same_resource_id_frames_count_ = 0;
+
   return false;
-  }
 }
 
 bool OverlayStrategySingleOnTop::TryOverlay(

components/viz/service/display/overlay_strategy_single_on_top.h

@@ -31,8 +31,6 @@ class VIZ_SERVICE_EXPORT OverlayStrategySingleOnTop
   OverlayStrategy GetUMAEnum() const override;
 
  private:
-  static constexpr size_t kMaxFrameCandidateWithSameResourceId = 3;
-
   bool TryOverlay(QuadList* quad_list,
                   OverlayCandidateList* candidate_list,
                   const OverlayCandidate& candidate,
@@ -40,9 +38,6 @@ class VIZ_SERVICE_EXPORT OverlayStrategySingleOnTop
 
   OverlayCandidateValidator* capability_checker_;  // Weak.
 
-  ResourceId previous_frame_resource_id_ = kInvalidResourceId;
-  size_t same_resource_id_frames_count_ = 0;
-
   DISALLOW_COPY_AND_ASSIGN(OverlayStrategySingleOnTop);
 };
 

components/viz/service/display/overlay_unittest.cc

@@ -1582,70 +1582,6 @@ TEST_F(SingleOverlayOnTopTest, RejectTransparentColorOnTopWithoutBlending) {
   EXPECT_EQ(0U, candidate_list.size());
 }
 
-TEST_F(SingleOverlayOnTopTest, DoNotPromoteIfContentsDontChange) {
-  // Resource ID for the repeated quads. Value should be equivalent to
-  // OverlayStrategySingleOnTop::kMaxFrameCandidateWithSameResourceId.
-  constexpr size_t kFramesSkippedBeforeNotPromoting = 3;
-  ResourceId previous_resource_id;
-
-  for (size_t i = 0; i < 3 + kFramesSkippedBeforeNotPromoting; ++i) {
-    std::unique_ptr<RenderPass> pass = CreateRenderPass();
-    RenderPass* main_pass = pass.get();
-
-    ResourceId resource_id;
-    if (i == 0 || i == 1) {
-      // Create a unique resource only for the first 2 frames.
-      resource_id = CreateResource(
-          resource_provider_.get(), child_resource_provider_.get(),
-          child_provider_.get(), pass->output_rect.size(),
-          true /*is_overlay_candidate*/);
-      previous_resource_id = resource_id;
-    } else {
-      // Starting the 3rd frame, they should have the same resource ID.
-      resource_id = previous_resource_id;
-    }
-
-    // Create a quad with the resource ID selected above.
-    TextureDrawQuad* original_quad =
-        main_pass->CreateAndAppendDrawQuad<TextureDrawQuad>();
-    float vertex_opacity[4] = {1.0f, 1.0f, 1.0f, 1.0f};
-    original_quad->SetNew(
-        pass->shared_quad_state_list.back(), pass->output_rect,
-        pass->output_rect, false /*needs_blending*/, resource_id,
-        false /*premultiplied_alpha*/, kUVTopLeft, kUVBottomRight,
-        SK_ColorTRANSPARENT, vertex_opacity, false /*flipped*/,
-        false /*nearest_neighbor*/, false /*secure_output_only*/,
-        ui::ProtectedVideoType::kClear);
-    original_quad->set_resource_size_in_pixels(pass->output_rect.size());
-
-    // Add something behind it.
-    CreateFullscreenOpaqueQuad(resource_provider_.get(),
-                               pass->shared_quad_state_list.back(), main_pass);
-
-    // Check for potential candidates.
-    OverlayCandidateList candidate_list;
-    OverlayProcessor::FilterOperationsMap render_pass_filters;
-    OverlayProcessor::FilterOperationsMap render_pass_backdrop_filters;
-    RenderPassList pass_list;
-    pass_list.push_back(std::move(pass));
-    overlay_processor_->ProcessForOverlays(
-        resource_provider_.get(), &pass_list, GetIdentityColorMatrix(),
-        render_pass_filters, render_pass_backdrop_filters, &candidate_list,
-        nullptr, nullptr, &damage_rect_, &content_bounds_);
-
-    if (i <= kFramesSkippedBeforeNotPromoting) {
-      EXPECT_EQ(1U, candidate_list.size());
-      // Check that the right resource id got extracted.
-      EXPECT_EQ(resource_id, candidate_list.back().resource_id);
-      // Check that the quad is gone.
-      EXPECT_EQ(1U, main_pass->quad_list.size());
-    } else {
-      // Check nothing has been promoted.
-      EXPECT_EQ(2U, main_pass->quad_list.size());
-    }
-  }
-}
-
 TEST_F(UnderlayTest, OverlayLayerUnderMainLayer) {
   AddExpectedRectToOverlayValidator(gfx::RectF(kOverlayBottomRightRect));