Reimplement chrome_pdf::Image using absl::variant

Now that we're allowed to use absl::variant, reimplement Image to use an
absl::variant<pp::ImageData, SkBitmap> internally. Behavior should
remain largely the same, with slightly less memory overhead.

Bug: 1099020
Change-Id: Ia4b2398ceae6156997be8904562778d47af97e32
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2333538Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Commit-Queue: K. Moon <kmoon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#794775}

pdf/BUILD.gn

@@ -196,6 +196,8 @@ if (enable_pdf) {
 
     configs += [ ":pdf_common_config" ]
 
+    public_deps = [ "//third_party/abseil-cpp:absl" ]
+
     deps = [
       "//base",
       "//ppapi/cpp:objects",
@@ -214,6 +216,8 @@ if (enable_pdf) {
 
     configs += [ ":pdf_common_config" ]
 
+    public_deps = [ "//third_party/abseil-cpp:absl" ]
+
     deps = [
       ":features",
       ":internal",

pdf/ppapi_migration/image.cc

@@ -5,13 +5,14 @@
 #include "pdf/ppapi_migration/image.h"
 
 #include "ppapi/cpp/image_data.h"
+#include "third_party/abseil-cpp/absl/types/variant.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 
 namespace chrome_pdf {
 
-Image::Image(const pp::ImageData& pepper_image) : pepper_image_(pepper_image) {}
+Image::Image(const pp::ImageData& pepper_image) : image_(pepper_image) {}
 
-Image::Image(const SkBitmap& skia_image) : skia_image_(skia_image) {}
+Image::Image(const SkBitmap& skia_image) : image_(skia_image) {}
 
 Image::Image(const Image& other) = default;
 

pdf/ppapi_migration/image.h

@@ -5,8 +5,8 @@
 #ifndef PDF_PPAPI_MIGRATION_IMAGE_H_
 #define PDF_PPAPI_MIGRATION_IMAGE_H_
 
-#include "base/check.h"
 #include "ppapi/cpp/image_data.h"
+#include "third_party/abseil-cpp/absl/types/variant.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 
 namespace chrome_pdf {
@@ -24,18 +24,13 @@ class Image final {
   ~Image();
 
   const pp::ImageData& pepper_image() const {
-    DCHECK(skia_image_.isNull());
-    return pepper_image_;
+    return absl::get<pp::ImageData>(image_);
   }
 
-  const SkBitmap& skia_image() const {
-    DCHECK(pepper_image_.is_null());
-    return skia_image_;
-  }
+  const SkBitmap& skia_image() const { return absl::get<SkBitmap>(image_); }
 
  private:
-  pp::ImageData pepper_image_;
-  SkBitmap skia_image_;
+  absl::variant<pp::ImageData, SkBitmap> image_;
 };
 
 }  // namespace chrome_pdf