[iOS] Have showcase bundle web resources

//ios/web, like //content, has a general assumption that it should be
able to get at its own internal resources via WebClient::GetDataResource().

This is currently not true among all //ios/web embedders, but an upcoming
CL will rely on this functionality. This CL adds bundling of iOS web
resources into Showcase and makes those resources available to //ios/web.

In an ideal world, it seems that Showcase wouldn't be an //ios/web embedder
at all, in which case these requirements would become irrelevant for
Showcase.

Bug: 731588
Change-Id: I19b2f9b103bfe5674ee3e2100cb40174cd30dc4c
Reviewed-on: https://chromium-review.googlesource.com/558063
Commit-Queue: Colin Blundell <blundell@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#484010}

ios/showcase/BUILD.gn

@@ -6,6 +6,7 @@ import("//build/config/ios/rules.gni")
 import("//ios/build/chrome_build.gni")
 import("//ios/build/config.gni")
 import("//ios/third_party/earl_grey/ios_eg_test.gni")
+import("//tools/grit/repack.gni")
 
 ios_app_bundle("showcase") {
   info_plist = "core/Info.plist"
@@ -47,11 +48,23 @@ group("all_tests") {
   ]
 }
 
+repack("packed_resources") {
+  sources = [
+    "$root_gen_dir/ios/web/ios_web_resources.pak",
+  ]
+  deps = [
+    "//ios/web:resources",
+  ]
+  output = "$target_gen_dir/showcase_resources.pak"
+  copy_data_to_bundle = true
+}
+
 ios_eg_test("ios_showcase_egtests") {
   info_plist = "core/Info.plist"
   extra_substitutions = [ "IOS_BUNDLE_ID_PREFIX=$ios_app_bundle_id_prefix" ]
   deps = [
     ":features",
+    ":packed_resources",
     "//ios/showcase/core:main",
 
     # Add all eg_tests targets below.

ios/showcase/DEPS

@@ -4,5 +4,6 @@ include_rules = [
   "+ios/clean",
   "+ios/third_party/material_components_ios",
   "+ios/third_party/material_roboto_font_loader_ios",
+  "+ios/web/public",
   "+ui/base",
 ]

ios/showcase/core/BUILD.gn

@@ -17,6 +17,11 @@ source_set("core") {
     "//ios/showcase/common",
     "//ios/third_party/material_components_ios",
     "//ios/third_party/material_roboto_font_loader_ios",
+
+    # TODO(crbug.com/738880): Showcase ideally shouldn't be an embedder of
+    # //ios/web.
+    "//ios/web",
+    "//ios/web/public/app",
     "//ui/base",
   ]
   libs = [ "UIKit.framework" ]

ios/showcase/core/app_delegate.mm

@@ -5,10 +5,13 @@
 #import "ios/showcase/core/app_delegate.h"
 
 #include "base/memory/ptr_util.h"
+#include "base/path_service.h"
 #include "ios/chrome/app/startup/ios_chrome_main.h"
 #import "ios/showcase/core/showcase_model.h"
 #import "ios/showcase/core/showcase_view_controller.h"
 #import "ios/third_party/material_components_ios/src/components/Typography/src/MaterialTypography.h"
+#import "ios/web/public/app/web_main_parts.h"
+#import "ios/web/public/web_client.h"
 #include "ui/base/resource/resource_bundle.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
@@ -18,6 +21,42 @@
 @implementation AppDelegate
 @synthesize window = _window;
 
+namespace {
+
+class ShowcaseWebMainParts : public web::WebMainParts {
+  void PreMainMessageLoopStart() override {
+    ResourceBundle::InitSharedInstanceWithLocale(
+        std::string(), nullptr, ResourceBundle::LOAD_COMMON_RESOURCES);
+
+    base::FilePath pak_path;
+    PathService::Get(base::DIR_MODULE, &pak_path);
+    ResourceBundle::GetSharedInstance().AddDataPackFromPath(
+        pak_path.AppendASCII("showcase_resources.pak"), ui::SCALE_FACTOR_100P);
+  }
+};
+
+class ShowcaseWebClient : public web::WebClient {
+ public:
+  ShowcaseWebClient() {}
+  ~ShowcaseWebClient() override {}
+
+  // WebClient implementation.
+  std::unique_ptr<web::WebMainParts> CreateWebMainParts() override {
+    return base::MakeUnique<ShowcaseWebMainParts>();
+  }
+  base::StringPiece GetDataResource(
+      int resource_id,
+      ui::ScaleFactor scale_factor) const override {
+    return ResourceBundle::GetSharedInstance().GetRawDataResourceForScale(
+        resource_id, scale_factor);
+  }
+  base::RefCountedMemory* GetDataResourceBytes(int resource_id) const override {
+    return ResourceBundle::GetSharedInstance().LoadDataResourceBytes(
+        resource_id);
+  }
+};
+}
+
 - (void)setupUI {
   ShowcaseViewController* viewController =
       [[ShowcaseViewController alloc] initWithRows:[AppDelegate rowsToDisplay]];
@@ -30,9 +69,12 @@ - (void)setupUI {
 
 - (BOOL)application:(UIApplication*)application
     didFinishLaunchingWithOptions:(NSDictionary*)launchOptions {
+  // TODO(crbug.com/738880): Showcase ideally shouldn't be an embedder of
+  // //ios/web, in which case it wouldn't have to do this. This almost
+  // certainly means not creating IOSChromeMain.
+  web::SetWebClient(new ShowcaseWebClient());
   base::MakeUnique<IOSChromeMain>();
-  ResourceBundle::InitSharedInstanceWithLocale(
-      std::string(), nullptr, ResourceBundle::LOAD_COMMON_RESOURCES);
+
   self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
   [self setupUI];
   [self.window makeKeyAndVisible];