[Paint Preview] static_library -> source_set

This might save on binary size, but regardless it is good to change.
This was made a static_library at project start and should have been a
source_set.

Change-Id: I925848a98d299c106e007f1770d54b984f414e46
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2570239
Auto-Submit: Calder Kitagawa <ckitagawa@chromium.org>
Commit-Queue: Mehran Mahmoudi <mahmoudi@chromium.org>
Reviewed-by: Mehran Mahmoudi <mahmoudi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#833300}

components/paint_preview/renderer/BUILD.gn

@@ -4,8 +4,9 @@
 
 import("//testing/test.gni")
 
-if (!is_ios) {
-  static_library("renderer") {
+assert(!is_ios, "Paint Previews are not supported on iOS.")
+
+source_set("renderer") {
   sources = [
     "paint_preview_recorder_impl.cc",
     "paint_preview_recorder_impl.h",
@@ -26,9 +27,9 @@ if (!is_ios) {
     "//components/paint_preview/common",
     "//components/paint_preview/common/mojom",
   ]
-  }
+}
 
-  source_set("unit_tests") {
+source_set("unit_tests") {
   testonly = true
 
   sources = [ "paint_preview_recorder_utils_unittest.cc" ]
@@ -42,14 +43,13 @@ if (!is_ios) {
     "//testing/gmock",
     "//testing/gtest",
   ]
-  }
+}
 
-  test("paint_preview_renderer_unit_tests") {
+test("paint_preview_renderer_unit_tests") {
   deps = [
     ":unit_tests",
     "//base",
     "//base/test:test_support",
     "//components/test:run_all_unittests",
   ]
-  }
 }