Revert of Revert of Introduce HostID and de-couple Extensions from "script injection System" [browser side]

chrome/browser/extensions/extension_user_script_loader.cc

Index: chrome/browser/extensions/extension_user_script_loader.cc
diff --git a/chrome/browser/extensions/extension_user_script_loader.cc b/chrome/browser/extensions/extension_user_script_loader.cc
new file mode 100644
index 0000000000000000000000000000000000000000..0104f5a20428da8cf4052c000b8a9516779a986b
--- /dev/null
+++ b/chrome/browser/extensions/extension_user_script_loader.cc
@@ -0,0 +1,166 @@
+// Copyright 2015 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/extensions/extension_user_script_loader.h"
+
+#include <set>
+#include <string>
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
+#include "base/version.h"
+#include "chrome/browser/profiles/profile.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/notification_service.h"
+#include "content/public/browser/render_process_host.h"
+#include "extensions/browser/component_extension_resource_manager.h"
+#include "extensions/browser/content_verifier.h"
+#include "extensions/browser/extension_registry.h"
+#include "extensions/browser/extension_system.h"
+#include "extensions/browser/extensions_browser_client.h"
+#include "extensions/common/file_util.h"
+#include "extensions/common/manifest_handlers/default_locale_handler.h"
+#include "extensions/common/message_bundle.h"
+#include "extensions/common/one_shot_event.h"
+#include "ui/base/resource/resource_bundle.h"
+
+namespace extensions {
+
+namespace {
+
+// Verifies file contents as they are read.
+void VerifyContent(const scoped_refptr<ContentVerifier>& verifier,
+                   const std::string& extension_id,
+                   const base::FilePath& extension_root,
+                   const base::FilePath& relative_path,
+                   const std::string& content) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
+  scoped_refptr<ContentVerifyJob> job(
+      verifier->CreateJobFor(extension_id, extension_root, relative_path));
+  if (job.get()) {
+    job->Start();
+    job->BytesRead(content.size(), content.data());
+    job->DoneReading();
+  }
+}
+
+// Loads user scripts from the extension who owns these scripts.
+bool ExtensionLoadScriptContent(
+    const HostID& host_id,
+    UserScript::File* script_file,
+    const UserScriptLoader::SubstitutionMap* localization_messages,
+    const scoped_refptr<ContentVerifier>& verifier) {
+  DCHECK(script_file);
+  std::string content;
+  const base::FilePath& path = ExtensionResource::GetFilePath(
+      script_file->extension_root(), script_file->relative_path(),
+      ExtensionResource::SYMLINKS_MUST_RESOLVE_WITHIN_ROOT);
+  if (path.empty()) {
+    int resource_id = 0;
+    if (ExtensionsBrowserClient::Get()
+            ->GetComponentExtensionResourceManager()
+            ->IsComponentExtensionResource(script_file->extension_root(),
+                                           script_file->relative_path(),
+                                           &resource_id)) {
+      const ResourceBundle& rb = ResourceBundle::GetSharedInstance();
+      content = rb.GetRawDataResource(resource_id).as_string();
+    } else {
+      LOG(WARNING) << "Failed to get file path to "
+                   << script_file->relative_path().value() << " from "
+                   << script_file->extension_root().value();
+      return false;
+    }
+  } else {
+    if (!base::ReadFileToString(path, &content)) {
+      LOG(WARNING) << "Failed to load user script file: " << path.value();
+      return false;
+    }
+    if (verifier.get()) {
+      content::BrowserThread::PostTask(
+          content::BrowserThread::IO, FROM_HERE,
+          base::Bind(&VerifyContent, verifier, host_id.id(),
+                     script_file->extension_root(),
+                     script_file->relative_path(), content));
+    }
+  }
+
+  // Localize the content.
+  if (localization_messages) {
+    std::string error;
+    MessageBundle::ReplaceMessagesWithExternalDictionary(*localization_messages,
+                                                         &content, &error);
+    if (!error.empty())
+      LOG(WARNING) << "Failed to replace messages in script: " << error;
+  }
+
+  // Remove BOM from the content.
+  std::string::size_type index = content.find(base::kUtf8ByteOrderMark);
+  if (index == 0)
+    script_file->set_content(content.substr(strlen(base::kUtf8ByteOrderMark)));
+  else
+    script_file->set_content(content);
+
+  return true;
+}
+
+}  // namespace
+
+ExtensionUserScriptLoader::ExtensionUserScriptLoader(
+    Profile* profile,
+    const HostID& host_id,
+    bool listen_for_extension_system_loaded)
+    : UserScriptLoader(profile,
+                       host_id,
+                       ExtensionSystem::Get(profile)->content_verifier()),
+      extension_registry_observer_(this),
+      weak_factory_(this) {
+  extension_registry_observer_.Add(ExtensionRegistry::Get(profile));
+  if (listen_for_extension_system_loaded) {
+    ExtensionSystem::Get(profile)->ready().Post(
+        FROM_HERE,
+        base::Bind(&ExtensionUserScriptLoader::OnExtensionSystemReady,
+                   weak_factory_.GetWeakPtr()));
+  } else {
+    SetReady(true);
+  }
+}
+
+ExtensionUserScriptLoader::~ExtensionUserScriptLoader() {
+}
+
+void ExtensionUserScriptLoader::UpdateHostsInfo(
+    const std::set<HostID>& changed_hosts) {
+  ExtensionRegistry* registry = ExtensionRegistry::Get(profile());
+  for (const HostID& host_id : changed_hosts) {
+    const Extension* extension =
+        registry->GetExtensionById(host_id.id(), ExtensionRegistry::ENABLED);
+    // |changed_hosts_| may include hosts that have been removed,
+    // which leads to the above lookup failing. In this case, just continue.
+    if (!extension)
+      continue;
+    AddHostInfo(host_id, ExtensionSet::ExtensionPathAndDefaultLocale(
+                             extension->path(),
+                             LocaleInfo::GetDefaultLocale(extension)));
+  }
+}
+
+UserScriptLoader::LoadUserScriptsContentFunction
+ExtensionUserScriptLoader::GetLoadUserScriptsFunction() {
+  return base::Bind(&ExtensionLoadScriptContent);
+}
+
+void ExtensionUserScriptLoader::OnExtensionUnloaded(
+    content::BrowserContext* browser_context,
+    const Extension* extension,
+    UnloadedExtensionInfo::Reason reason) {
+  RemoveHostInfo(HostID(HostID::EXTENSIONS, extension->id()));
+}
+
+void ExtensionUserScriptLoader::OnExtensionSystemReady() {
+  SetReady(true);
+}
+
+}  // namespace extensions