[Dark mode]: fix bugs with gradients in dark mode.

- Always apply dark mode filter to the gradients in dark mode.
- Apply dark mode filter if applicable to rounded images.

Bug: 936890
Change-Id: Ic1113b201eaab1d0803e67232364623e143a5e98
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1520681Reviewed-by: Stephen Chenney <schenney@chromium.org>
Reviewed-by: Tobias Sargeant <tobiasjs@chromium.org>
Commit-Queue: Anna Malova <amalova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#649161}

third_party/blink/renderer/platform/graphics/gradient_generated_image.h

@@ -44,6 +44,10 @@ class PLATFORM_EXPORT GradientGeneratedImage final : public GeneratedImage {
   ~GradientGeneratedImage() override = default;
 
   bool ApplyShader(PaintFlags&, const SkMatrix&) override;
+  DarkModeClassification ClassifyImageForDarkMode(
+      const FloatRect& src_rect) override {
+    return DarkModeClassification::kApplyDarkModeFilter;
+  }
 
  protected:
   void Draw(cc::PaintCanvas*,

third_party/blink/renderer/platform/graphics/graphics_context.cc

@@ -951,6 +951,8 @@ void GraphicsContext::DrawImageRRect(
   image_flags.setColor(SK_ColorBLACK);
   image_flags.setFilterQuality(
       ComputeFilterQuality(image, dest.Rect(), src_rect));
+  if (ShouldApplyDarkModeFilterToImage(*image, src_rect))
+    image_flags.setColorFilter(dark_mode_filter_);
 
   bool use_shader = (visible_src == src_rect) &&
                     (respect_orientation == kDoNotRespectImageOrientation);