Move pdf/ppapi_migration code into its own target.

Move more code that depends on PPAPI out of the "internal" build target.

Bug: 1103478
Change-Id: Ifa7b2ca0565a261ca0493d97dab9bf216d47f35f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2308490
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Daniel Hosseinian <dhoss@chromium.org>
Cr-Commit-Position: refs/heads/master@{#790576}

pdf/BUILD.gn

@@ -121,14 +121,6 @@ if (enable_pdf) {
       "pdfium/pdfium_range.h",
       "pdfium/pdfium_unsupported_features.cc",
       "pdfium/pdfium_unsupported_features.h",
-      "ppapi_migration/bitmap.cc",
-      "ppapi_migration/bitmap.h",
-      "ppapi_migration/callback.cc",
-      "ppapi_migration/callback.h",
-      "ppapi_migration/geometry_conversions.cc",
-      "ppapi_migration/geometry_conversions.h",
-      "ppapi_migration/input_event_conversions.cc",
-      "ppapi_migration/input_event_conversions.h",
       "preview_mode_client.cc",
       "preview_mode_client.h",
       "range_set.cc",
@@ -142,6 +134,7 @@ if (enable_pdf) {
 
     deps = [
       ":features",
+      ":ppapi_migration",
       "//base",
       "//base:i18n",
       "//gin",
@@ -174,12 +167,37 @@ if (enable_pdf) {
     deps = [
       ":internal",
       ":pdf",
+      ":ppapi_migration",
       "//ppapi/c",
       "//third_party/pdfium",
       "//ui/base",
     ]
   }
 
+  source_set("ppapi_migration") {
+    visibility = [ ":*" ]
+
+    sources = [
+      "ppapi_migration/bitmap.cc",
+      "ppapi_migration/bitmap.h",
+      "ppapi_migration/callback.cc",
+      "ppapi_migration/callback.h",
+      "ppapi_migration/geometry_conversions.cc",
+      "ppapi_migration/geometry_conversions.h",
+      "ppapi_migration/input_event_conversions.cc",
+      "ppapi_migration/input_event_conversions.h",
+    ]
+
+    configs += [ ":pdf_common_config" ]
+
+    deps = [
+      "//base",
+      "//ppapi/cpp:objects",
+      "//skia",
+      "//ui/base",
+    ]
+  }
+
   source_set("out_of_process_instance") {
     visibility = [ ":*" ]
 
@@ -193,6 +211,7 @@ if (enable_pdf) {
     deps = [
       ":features",
       ":internal",
+      ":ppapi_migration",
       "//base",
       "//net",
       "//ppapi/cpp:objects",
@@ -265,6 +284,7 @@ if (enable_pdf) {
       ":out_of_process_instance",
       ":pdf",
       ":pdf_test_utils",
+      ":ppapi_migration",
       "//base",
       "//base/test:run_all_unittests",
       "//base/test:test_support",