[DevUI DFM] Add helpers to load native resources in "dev_ui_resources.pak".

This CL adds helper functions to load DevUI DFM native resources.
* Add enum chrome::FILE_DEV_UI_RESOURCES_PACK to specify path for
  "dev_ui_resources.pak" on Android.
* Add LoadAndroidDevUiPackFile().
  * Adds another {file descriptor, memory mapped file regions} global
    variable in resource_bundle_android.h. All these will be cleaned up
    in the future.
* Add LoadDevUiResources() (in new file) as the main function to call
  to load DevUI DFM resources (hidden behind DFMIFY_DEV_UI).
  * There's no need for a function to return the file descriptor of
    "dev_ui_resources.pak", because we do not intend to forward it to
    child processes.

Bug: 927131
Change-Id: I0c4e42e33b959d0a022f1287748573ebaf79c685
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1769218Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Samuel Huang <huangs@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#691672}

chrome/browser/BUILD.gn

@@ -35,6 +35,7 @@ import("//ui/base/ui_features.gni")
 # produces a conflict for the "grit" template so we have to only include one.
 if (is_android) {
   import("//build/config/android/rules.gni")
+  import("//chrome/android/features/dev_ui/dev_ui_module.gni")
 } else {
   import("//tools/grit/grit_rule.gni")
 }
@@ -2380,6 +2381,8 @@ jumbo_split_static_library("browser") {
       "android/devtools_manager_delegate_android.h",
       "android/devtools_server.cc",
       "android/devtools_server.h",
+      "android/dfm_resource_bundle_helper.cc",
+      "android/dfm_resource_bundle_helper.h",
       "android/digital_asset_links/digital_asset_links_handler.cc",
       "android/digital_asset_links/digital_asset_links_handler.h",
       "android/document/document_web_contents_delegate.cc",
@@ -2884,6 +2887,7 @@ jumbo_split_static_library("browser") {
       "translate/android/translate_bridge.cc",
     ]
     public_deps += [
+      "//chrome/android/features/dev_ui:buildflags",
       "//components/image_fetcher/core",
       "//components/ntp_snippets",
     ]

chrome/browser/DEPS

@@ -3,6 +3,7 @@ include_rules = [
   "+cc/paint",
   "+chrome/android/chrome_jni_headers",
   "+chrome/android/features/autofill_assistant/jni_headers",
+  "+chrome/android/features/dev_ui",
   "+chrome/android/public/profiles/jni_headers",
   "+chrome/app",
   "+chrome/chrome_watcher",

chrome/browser/android/dfm_resource_bundle_helper.cc

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "chrome/browser/android/dfm_resource_bundle_helper.h"
+
+#include "base/logging.h"
+
+#include "base/path_service.h"
+#include "chrome/common/chrome_paths.h"
+#include "ui/base/resource/resource_bundle_android.h"
+
+namespace android {
+
+#if BUILDFLAG(DFMIFY_DEV_UI)
+void LoadDevUiResources() {
+  base::FilePath path_on_disk;
+  base::PathService::Get(chrome::FILE_DEV_UI_RESOURCES_PACK, &path_on_disk);
+  ui::LoadAndroidDevUiPackFile("assets/dev_ui_resources.pak", path_on_disk);
+}
+#endif  // BUILDFLAG(DFMIFY_DEV_UI)
+
+}  // namespace android

chrome/browser/android/dfm_resource_bundle_helper.h

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_ANDROID_DFM_RESOURCE_BUNDLE_HELPER_H_
+#define CHROME_BROWSER_ANDROID_DFM_RESOURCE_BUNDLE_HELPER_H_
+
+#include "chrome/android/features/dev_ui/buildflags.h"
+
+namespace android {
+
+#if BUILDFLAG(DFMIFY_DEV_UI)
+// Loads the resources for DevUI pages. Performs file I/O, and should be called
+// on a worker thread.
+void LoadDevUiResources();
+#endif  // BUILDFLAG(DFMIFY_DEV_UI)
+
+}  // namespace android
+
+#endif  // CHROME_BROWSER_ANDROID_DFM_RESOURCE_BUNDLE_HELPER_H_

chrome/common/chrome_paths.cc

@@ -383,7 +383,8 @@ bool PathProvider(int key, base::FilePath* result) {
               .AppendASCII(base::GetNativeLibraryName(kWidevineCdmLibraryName));
       break;
 #endif  // BUILDFLAG(ENABLE_WIDEVINE) && BUILDFLAG(ENABLE_LIBRARY_CDMS)
-    case chrome::FILE_RESOURCES_PACK:
+    case chrome::FILE_RESOURCES_PACK:  // Falls through.
+    case chrome::FILE_DEV_UI_RESOURCES_PACK:
 #if defined(OS_MACOSX)
       cur = base::mac::FrameworkBundlePath();
       cur = cur.Append(FILE_PATH_LITERAL("Resources"))
@@ -392,14 +393,21 @@ bool PathProvider(int key, base::FilePath* result) {
 #elif defined(OS_ANDROID)
       if (!base::PathService::Get(ui::DIR_RESOURCE_PAKS_ANDROID, &cur))
         return false;
+      if (key == chrome::FILE_DEV_UI_RESOURCES_PACK) {
+        cur = cur.Append(FILE_PATH_LITERAL("dev_ui_resources.pak"));
+      } else {
+        DCHECK_EQ(chrome::FILE_RESOURCES_PACK, key);
+        cur = cur.Append(FILE_PATH_LITERAL("resources.pak"));
+      }
 #else
       // If we're not bundled on mac or Android, resources.pak should be next
       // to the binary (e.g., for unit tests).
       if (!base::PathService::Get(base::DIR_MODULE, &cur))
         return false;
-#endif
       cur = cur.Append(FILE_PATH_LITERAL("resources.pak"));
+#endif
       break;
+
 #if defined(OS_CHROMEOS)
     case chrome::DIR_CHROMEOS_WALLPAPERS:
       if (!base::PathService::Get(chrome::DIR_USER_DATA, &cur))

chrome/common/chrome_paths.h

@@ -94,9 +94,13 @@ enum {
   DIR_PNACL_COMPONENT,              // Full path to the latest PNaCl version
                                     // (subdir of DIR_PNACL_BASE).
   FILE_WIDEVINE_CDM,                // Full path to the Widevine CDM.
-  FILE_RESOURCES_PACK,              // Full path to the .pak file containing
-                                    // binary data (e.g., html files and images
-                                    // used by internal pages).
+  FILE_RESOURCES_PACK,  // Full path to the .pak file containing binary data.
+                        // This includes data for internal pages (e.g., html
+                        // files and images), unless these resources are
+                        // purposefully split into a separate file.
+  FILE_DEV_UI_RESOURCES_PACK,  // Full path to the .pak file containing
+                               // binary data for internal pages (e.g., html
+                               // files and images).
 #if defined(OS_CHROMEOS)
   DIR_CHROMEOS_WALLPAPERS,            // Directory where downloaded chromeos
                                       // wallpapers reside.

ui/base/resource/resource_bundle_android.cc

@@ -25,10 +25,12 @@ bool g_load_secondary_locale_paks = false;
 // ResourceBundle singleton never closes the handles.
 int g_chrome_100_percent_fd = -1;
 int g_resources_pack_fd = -1;
+int g_dev_ui_resources_pack_fd = -1;
 int g_locale_pack_fd = -1;
 int g_secondary_locale_pack_fd = -1;
 base::MemoryMappedFile::Region g_chrome_100_percent_region;
 base::MemoryMappedFile::Region g_resources_pack_region;
+base::MemoryMappedFile::Region g_dev_ui_resources_pack_region;
 base::MemoryMappedFile::Region g_locale_pack_region;
 base::MemoryMappedFile::Region g_secondary_locale_pack_region;
 
@@ -177,6 +179,19 @@ void LoadMainAndroidPackFile(const char* path_within_apk,
   }
 }
 
+void LoadAndroidDevUiPackFile(const char* path_within_apk,
+                              const base::FilePath& disk_file_path) {
+  if (LoadFromApkOrFile(path_within_apk, &disk_file_path,
+                        &g_dev_ui_resources_pack_fd,
+                        &g_dev_ui_resources_pack_region)) {
+    ResourceBundle::GetSharedInstance().AddDataPackFromFileRegion(
+        base::File(g_dev_ui_resources_pack_fd), g_dev_ui_resources_pack_region,
+        SCALE_FACTOR_NONE);
+  } else {
+    NOTREACHED() << "Failed to load DevUI resources.";
+  }
+}
+
 int GetMainAndroidPackFd(base::MemoryMappedFile::Region* out_region) {
   DCHECK_GE(g_resources_pack_fd, 0);
   *out_region = g_resources_pack_region;

ui/base/resource/resource_bundle_android.h

@@ -14,11 +14,17 @@
 namespace ui {
 
 // Loads "resources.apk" from the .apk. Falls back to loading from disk, which
-// is necessary for tests. Returns true if it succeeds, false otherwise.
+// is necessary for tests.
 UI_BASE_EXPORT void LoadMainAndroidPackFile(
     const char* path_within_apk,
     const base::FilePath& disk_file_path);
 
+// Loads "dev_ui_resources.apk" from the .apk, for the DevUI DFM. Falls back to
+// loading from disk.
+UI_BASE_EXPORT void LoadAndroidDevUiPackFile(
+    const char* path_within_apk,
+    const base::FilePath& disk_file_path);
+
 // Returns the file descriptor and region for resources.pak.
 UI_BASE_EXPORT int GetMainAndroidPackFd(
     base::MemoryMappedFile::Region* out_region);