[PDF] Delete old code path that PdfPaintManagerDrawsBackground replaced

Now that https://crrev.com/1370910 has reached Stable channel, delete
the PdfPaintManagerDrawsBackground kill switch and the old code path
that is now unreachable.

Bug: 40216952
Change-Id: Idc3f5ea612e660335b08a22977e61030f5ec9cfa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6216505
Reviewed-by: Andy Phan <andyphan@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1415716}

pdf/paint_manager.cc

@@ -289,15 +289,12 @@ void PaintManager::DoPaint() {
   for (const auto& ready_rect : ready_now) {
     const SkRect skia_rect = gfx::RectToSkRect(ready_rect.rect());
 
-    if (base::FeatureList::IsEnabled(
-            features::kPdfPaintManagerDrawsBackground)) {
-      // Paint the page's white background, and then paint the page's contents.
-      // If `ready_rect.image()` has transparencies, this is necessary to paint
-      // over the stale data in `skia_rect` in `surface_`.
-      SkPaint paint;
-      paint.setColor(SK_ColorWHITE);
-      surface_->getCanvas()->drawRect(skia_rect, paint);
-    }
+    // Paint the page's white background, and then paint the page's contents.
+    // If `ready_rect.image()` has transparencies, this is necessary to paint
+    // over the stale data in `skia_rect` in `surface_`.
+    SkPaint paint;
+    paint.setColor(SK_ColorWHITE);
+    surface_->getCanvas()->drawRect(skia_rect, paint);
 
     surface_->getCanvas()->drawImageRect(
         ready_rect.image(), skia_rect, skia_rect, SkSamplingOptions(), nullptr,

pdf/pdf_features.cc

@@ -27,12 +27,6 @@ BASE_FEATURE(kPdfIncrementalLoading,
 
 BASE_FEATURE(kPdfOopif, "PdfOopif", base::FEATURE_DISABLED_BY_DEFAULT);
 
-// Kill switch in case this goes horribly wrong.
-// TODO(crbug.com/40216952): Remove after this lands safely in a Stable release.
-BASE_FEATURE(kPdfPaintManagerDrawsBackground,
-             "PdfPaintManagerDrawsBackground",
-             base::FEATURE_ENABLED_BY_DEFAULT);
-
 // "Partial loading" refers to loading only specific parts of the PDF.
 // TODO(crbug.com/40123601): Remove this once partial loading is fixed.
 BASE_FEATURE(kPdfPartialLoading,

pdf/pdf_features.h

@@ -19,7 +19,6 @@ BASE_DECLARE_FEATURE(kAccessiblePDFForm);
 BASE_DECLARE_FEATURE(kPdfCr23);
 BASE_DECLARE_FEATURE(kPdfIncrementalLoading);
 BASE_DECLARE_FEATURE(kPdfOopif);
-BASE_DECLARE_FEATURE(kPdfPaintManagerDrawsBackground);
 BASE_DECLARE_FEATURE(kPdfPartialLoading);
 BASE_DECLARE_FEATURE(kPdfPortfolio);
 BASE_DECLARE_FEATURE(kPdfSearchify);

pdf/pdf_view_web_plugin.cc

@@ -2330,17 +2330,11 @@ void PdfViewWebPlugin::OnViewportChanged(
   const gfx::Size new_image_size =
       PaintManager::GetNewContextSize(old_image_size, plugin_rect_.size());
   if (new_image_size != old_image_size) {
-    SkAlphaType alpha_type;
-    if (base::FeatureList::IsEnabled(
-            features::kPdfPaintManagerDrawsBackground)) {
-      alpha_type = kUnpremul_SkAlphaType;
-    } else {
-      alpha_type = kPremul_SkAlphaType;
-    }
     // Ignore the result. If the allocation fails, the image data buffer will be
     // empty and the code below will handle that.
-    (void)image_data_.tryAllocPixels(SkImageInfo::MakeN32(
-        new_image_size.width(), new_image_size.height(), alpha_type));
+    (void)image_data_.tryAllocPixels(
+        SkImageInfo::MakeN32(new_image_size.width(), new_image_size.height(),
+                             kUnpremul_SkAlphaType));
     first_paint_ = true;
   }
 

pdf/pdfium/pdfium_engine.cc

@@ -3212,26 +3212,20 @@ bool PDFiumEngine::ContinuePaint(size_t progressive_index,
   }
 
   const gfx::Rect& dirty = paint.rect();
-  const gfx::Rect pdfium_rect = GetPDFiumRect(paint.page_index(), dirty);
-
   const bool has_alpha = !!FPDFPage_HasTransparency(page);
-  uint32_t fill_color;
-  if (base::FeatureList::IsEnabled(features::kPdfPaintManagerDrawsBackground)) {
-    // When `has_alpha` is true, use a transparent bitmap to render correctly.
-    // If the bitmap was painted white, then certain blend operations would
-    // blend into the white color and draw incorrectly. Instead, PaintManager
-    // will draw the white page under this bitmap.
-    fill_color = has_alpha ? 0x00000000 : 0xFFFFFFFF;
-  } else {
-    // In the old code, which is here as a fallback, `fill_color` is always
-    // white, as PaintManager does not draw the page's background.
-    fill_color = 0xFFFFFFFF;
-  }
   ScopedFPDFBitmap new_bitmap = CreateBitmap(dirty, has_alpha, image_data);
   FPDF_BITMAP new_bitmap_ptr = new_bitmap.get();
   paint.SetBitmapAndImageData(std::move(new_bitmap), image_data);
+
+  const gfx::Rect pdfium_rect = GetPDFiumRect(paint.page_index(), dirty);
+  // When `has_alpha` is true, use a transparent bitmap to render correctly.
+  // If the bitmap was painted white, then certain blend operations would
+  // blend into the white color and draw incorrectly. Instead, PaintManager
+  // will draw the white page under this bitmap.
+  const uint32_t fill_color = has_alpha ? 0x00000000 : 0xFFFFFFFF;
   FPDFBitmap_FillRect(new_bitmap_ptr, pdfium_rect.x(), pdfium_rect.y(),
                       pdfium_rect.width(), pdfium_rect.height(), fill_color);
+
   return FPDF_RenderPageBitmap_Start(
              new_bitmap_ptr, page, pdfium_rect.x(), pdfium_rect.y(),
              pdfium_rect.width(), pdfium_rect.height(),

pdf/pdfium/pdfium_page.cc

@@ -1833,12 +1833,6 @@ Thumbnail PDFiumPage::GenerateThumbnail(float device_pixel_ratio) {
   FPDF_PAGE page = GetPage();
   const bool has_alpha = !!FPDFPage_HasTransparency(page);
   const int format = has_alpha ? FPDFBitmap_BGRA : FPDFBitmap_BGRx;
-  uint32_t fill_color;
-  if (base::FeatureList::IsEnabled(features::kPdfPaintManagerDrawsBackground)) {
-    fill_color = has_alpha ? 0x00000000 : 0xFFFFFFFF;
-  } else {
-    fill_color = 0xFFFFFFFF;
-  }
 
   Thumbnail thumbnail = CreateThumbnail(device_pixel_ratio);
   const gfx::Size& image_size = thumbnail.image_size();
@@ -1848,6 +1842,7 @@ Thumbnail PDFiumPage::GenerateThumbnail(float device_pixel_ratio) {
       FPDFBitmap_CreateEx(image_size.width(), image_size.height(), format,
                           thumbnail.GetImageData().data(), thumbnail.stride()));
 
+  const uint32_t fill_color = has_alpha ? 0x00000000 : 0xFFFFFFFF;
   FPDFBitmap_FillRect(fpdf_bitmap.get(), /*left=*/0, /*top=*/0,
                       image_size.width(), image_size.height(), fill_color);