Move sandboxed_unpacker.{h,cc} from chrome/ to extensions/

This is a mostly mechanical change to move these files over, and
make corresponding changes to strings, build files, and include paths.

BUG=447014

Review URL: https://codereview.chromium.org/864093002

Cr-Commit-Position: refs/heads/master@{#313404}

17 files changed, 1314 insertions, 3 deletions

diff --git a/extensions/BUILD.gn b/extensions/BUILD.gn
index de53a9d..6fa4f48 100644
--- a/extensions/BUILD.gn
+++ b/extensions/BUILD.gn
@@ -102,6 +102,8 @@ source_set("test_support") {
     "test/extension_test_message_listener.h",
     "test/result_catcher.cc",
     "test/result_catcher.h",
+    "test/test_content_utility_client.cc",
+    "test/test_content_utility_client.h",
     "test/test_extensions_client.cc",
     "test/test_extensions_client.h",
     "test/test_permission_message_provider.cc",
@@ -212,6 +214,7 @@ if (false) {
       "browser/process_map_unittest.cc",
       "browser/quota_service_unittest.cc",
       "browser/runtime_data_unittest.cc",
+      "browser/sandboxed_unpacker_unittest.cc",
       "browser/value_store/leveldb_value_store_unittest.cc",
       "browser/value_store/testing_value_store_unittest.cc",
       "browser/value_store/value_store_change_unittest.cc",
diff --git a/extensions/DEPS b/extensions/DEPS
index 183bba6..a5faa35 100644
--- a/extensions/DEPS
+++ b/extensions/DEPS
@@ -11,9 +11,9 @@ include_rules = [
   "+extensions/test",
   "+grit/extensions_renderer_resources.h",
   "+grit/extensions_resources.h",
+  "+testing",
   "+third_party/mojo/src/mojo/public",
   "+third_party/skia/include",
-  "+testing",
 
   # Minimal UI dependencies. There are two good rules for UI dependencies here:
   #
diff --git a/extensions/browser/BUILD.gn b/extensions/browser/BUILD.gn
index 9cecc6c..092badd 100644
--- a/extensions/browser/BUILD.gn
+++ b/extensions/browser/BUILD.gn
@@ -475,6 +475,8 @@ source_set("browser") {
       "renderer_startup_helper.h",
       "runtime_data.cc",
       "runtime_data.h",
+      "sandboxed_unpacker.cc",
+      "sandboxed_unpacker.h",
       "script_execution_observer.h",
       "script_executor.cc",
       "script_executor.h",
diff --git a/extensions/browser/extensions_test.cc b/extensions/browser/extensions_test.cc
index 5b7a8ce..103ade0 100644
--- a/extensions/browser/extensions_test.cc
+++ b/extensions/browser/extensions_test.cc
@@ -9,6 +9,7 @@
 #include "content/public/common/content_client.h"
 #include "content/public/test/test_browser_context.h"
 #include "extensions/browser/test_extensions_browser_client.h"
+#include "extensions/test/test_content_utility_client.h"
 
 namespace extensions {
 
@@ -22,11 +23,13 @@ namespace extensions {
 // };
 ExtensionsTest::ExtensionsTest()
     : content_client_(new content::ContentClient),
+      content_utility_client_(new TestContentUtilityClient),
       content_browser_client_(new content::ContentBrowserClient),
       browser_context_(new content::TestBrowserContext),
       extensions_browser_client_(
           new TestExtensionsBrowserClient(browser_context_.get())) {
   content::SetContentClient(content_client_.get());
+  content::SetUtilityClientForTesting(content_utility_client_.get());
   content::SetBrowserClientForTesting(content_browser_client_.get());
   ExtensionsBrowserClient::Set(extensions_browser_client_.get());
 }
@@ -34,6 +37,7 @@ ExtensionsTest::ExtensionsTest()
 ExtensionsTest::~ExtensionsTest() {
   ExtensionsBrowserClient::Set(NULL);
   content::SetBrowserClientForTesting(NULL);
+  content::SetUtilityClientForTesting(NULL);
   content::SetContentClient(NULL);
 }
 
diff --git a/extensions/browser/extensions_test.h b/extensions/browser/extensions_test.h
index 3f5dd0a..ef71aee 100644
--- a/extensions/browser/extensions_test.h
+++ b/extensions/browser/extensions_test.h
@@ -12,8 +12,9 @@
 
 namespace content {
 class BrowserContext;
-class ContentClient;
 class ContentBrowserClient;
+class ContentClient;
+class ContentUtilityClient;
 }
 
 namespace extensions {
@@ -49,6 +50,7 @@ class ExtensionsTest : public testing::Test {
  private:
   // TODO(yoz): Add a NotificationService here; it's used widely enough.
   scoped_ptr<content::ContentClient> content_client_;
+  scoped_ptr<content::ContentUtilityClient> content_utility_client_;
   scoped_ptr<content::ContentBrowserClient> content_browser_client_;
   scoped_ptr<content::BrowserContext> browser_context_;
   scoped_ptr<TestExtensionsBrowserClient> extensions_browser_client_;
diff --git a/extensions/browser/sandboxed_unpacker.cc b/extensions/browser/sandboxed_unpacker.cc
new file mode 100644
index 0000000..cd535a8
--- /dev/null
+++ b/extensions/browser/sandboxed_unpacker.cc
@@ -0,0 +1,792 @@
+// Copyright (c) 2012 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 "extensions/browser/sandboxed_unpacker.h"
+
+#include <set>
+
+#include "base/base64.h"
+#include "base/bind.h"
+#include "base/command_line.h"
+#include "base/files/file_util.h"
+#include "base/files/file_util_proxy.h"
+#include "base/files/scoped_file.h"
+#include "base/json/json_string_value_serializer.h"
+#include "base/message_loop/message_loop.h"
+#include "base/metrics/histogram.h"
+#include "base/numerics/safe_conversions.h"
+#include "base/path_service.h"
+#include "base/sequenced_task_runner.h"
+#include "base/strings/utf_string_conversions.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "components/crx_file/constants.h"
+#include "components/crx_file/crx_file.h"
+#include "components/crx_file/id_util.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/utility_process_host.h"
+#include "content/public/common/common_param_traits.h"
+#include "crypto/signature_verifier.h"
+#include "extensions/common/constants.h"
+#include "extensions/common/extension.h"
+#include "extensions/common/extension_l10n_util.h"
+#include "extensions/common/extension_utility_messages.h"
+#include "extensions/common/extensions_client.h"
+#include "extensions/common/file_util.h"
+#include "extensions/common/manifest_constants.h"
+#include "extensions/common/manifest_handlers/icons_handler.h"
+#include "grit/extensions_strings.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/gfx/codec/png_codec.h"
+
+using base::ASCIIToUTF16;
+using content::BrowserThread;
+using content::UtilityProcessHost;
+using crx_file::CrxFile;
+
+// The following macro makes histograms that record the length of paths
+// in this file much easier to read.
+// Windows has a short max path length. If the path length to a
+// file being unpacked from a CRX exceeds the max length, we might
+// fail to install. To see if this is happening, see how long the
+// path to the temp unpack directory is. See crbug.com/69693 .
+#define PATH_LENGTH_HISTOGRAM(name, path) \
+  UMA_HISTOGRAM_CUSTOM_COUNTS(name, path.value().length(), 0, 500, 100)
+
+// Record a rate (kB per second) at which extensions are unpacked.
+// Range from 1kB/s to 100mB/s.
+#define UNPACK_RATE_HISTOGRAM(name, rate) \
+  UMA_HISTOGRAM_CUSTOM_COUNTS(name, rate, 1, 100000, 100);
+
+namespace extensions {
+namespace {
+
+void RecordSuccessfulUnpackTimeHistograms(const base::FilePath& crx_path,
+                                          const base::TimeDelta unpack_time) {
+  const int64 kBytesPerKb = 1024;
+  const int64 kBytesPerMb = 1024 * 1024;
+
+  UMA_HISTOGRAM_TIMES("Extensions.SandboxUnpackSuccessTime", unpack_time);
+
+  // To get a sense of how CRX size impacts unpack time, record unpack
+  // time for several increments of CRX size.
+  int64 crx_file_size;
+  if (!base::GetFileSize(crx_path, &crx_file_size)) {
+    UMA_HISTOGRAM_COUNTS("Extensions.SandboxUnpackSuccessCantGetCrxSize", 1);
+    return;
+  }
+
+  // Cast is safe as long as the number of bytes in the CRX is less than
+  // 2^31 * 2^10.
+  int crx_file_size_kb = static_cast<int>(crx_file_size / kBytesPerKb);
+  UMA_HISTOGRAM_COUNTS("Extensions.SandboxUnpackSuccessCrxSize",
+                       crx_file_size_kb);
+
+  // We have time in seconds and file size in bytes.  We want the rate bytes are
+  // unpacked in kB/s.
+  double file_size_kb =
+      static_cast<double>(crx_file_size) / static_cast<double>(kBytesPerKb);
+  int unpack_rate_kb_per_s =
+      static_cast<int>(file_size_kb / unpack_time.InSecondsF());
+  UNPACK_RATE_HISTOGRAM("Extensions.SandboxUnpackRate", unpack_rate_kb_per_s);
+
+  if (crx_file_size < 50.0 * kBytesPerKb) {
+    UNPACK_RATE_HISTOGRAM("Extensions.SandboxUnpackRateUnder50kB",
+                          unpack_rate_kb_per_s);
+
+  } else if (crx_file_size < 1 * kBytesPerMb) {
+    UNPACK_RATE_HISTOGRAM("Extensions.SandboxUnpackRate50kBTo1mB",
+                          unpack_rate_kb_per_s);
+
+  } else if (crx_file_size < 2 * kBytesPerMb) {
+    UNPACK_RATE_HISTOGRAM("Extensions.SandboxUnpackRate1To2mB",
+                          unpack_rate_kb_per_s);
+
+  } else if (crx_file_size < 5 * kBytesPerMb) {
+    UNPACK_RATE_HISTOGRAM("Extensions.SandboxUnpackRate2To5mB",
+                          unpack_rate_kb_per_s);
+
+  } else if (crx_file_size < 10 * kBytesPerMb) {
+    UNPACK_RATE_HISTOGRAM("Extensions.SandboxUnpackRate5To10mB",
+                          unpack_rate_kb_per_s);
+
+  } else {
+    UNPACK_RATE_HISTOGRAM("Extensions.SandboxUnpackRateOver10mB",
+                          unpack_rate_kb_per_s);
+  }
+}
+
+// Work horse for FindWritableTempLocation. Creates a temp file in the folder
+// and uses NormalizeFilePath to check if the path is junction free.
+bool VerifyJunctionFreeLocation(base::FilePath* temp_dir) {
+  if (temp_dir->empty())
+    return false;
+
+  base::FilePath temp_file;
+  if (!base::CreateTemporaryFileInDir(*temp_dir, &temp_file)) {
+    LOG(ERROR) << temp_dir->value() << " is not writable";
+    return false;
+  }
+  // NormalizeFilePath requires a non-empty file, so write some data.
+  // If you change the exit points of this function please make sure all
+  // exit points delete this temp file!
+  if (base::WriteFile(temp_file, ".", 1) != 1)
+    return false;
+
+  base::FilePath normalized_temp_file;
+  bool normalized = base::NormalizeFilePath(temp_file, &normalized_temp_file);
+  if (!normalized) {
+    // If |temp_file| contains a link, the sandbox will block al file system
+    // operations, and the install will fail.
+    LOG(ERROR) << temp_dir->value() << " seem to be on remote drive.";
+  } else {
+    *temp_dir = normalized_temp_file.DirName();
+  }
+  // Clean up the temp file.
+  base::DeleteFile(temp_file, false);
+
+  return normalized;
+}
+
+// This function tries to find a location for unpacking the extension archive
+// that is writable and does not lie on a shared drive so that the sandboxed
+// unpacking process can write there. If no such location exists we can not
+// proceed and should fail.
+// The result will be written to |temp_dir|. The function will write to this
+// parameter even if it returns false.
+bool FindWritableTempLocation(const base::FilePath& extensions_dir,
+                              base::FilePath* temp_dir) {
+// On ChromeOS, we will only attempt to unpack extension in cryptohome (profile)
+// directory to provide additional security/privacy and speed up the rest of
+// the extension install process.
+#if !defined(OS_CHROMEOS)
+  PathService::Get(base::DIR_TEMP, temp_dir);
+  if (VerifyJunctionFreeLocation(temp_dir))
+    return true;
+#endif
+
+  *temp_dir = file_util::GetInstallTempDir(extensions_dir);
+  if (VerifyJunctionFreeLocation(temp_dir))
+    return true;
+  // Neither paths is link free chances are good installation will fail.
+  LOG(ERROR) << "Both the %TEMP% folder and the profile seem to be on "
+             << "remote drives or read-only. Installation can not complete!";
+  return false;
+}
+
+// Read the decoded images back from the file we saved them to.
+// |extension_path| is the path to the extension we unpacked that wrote the
+// data. Returns true on success.
+bool ReadImagesFromFile(const base::FilePath& extension_path,
+                        DecodedImages* images) {
+  base::FilePath path = extension_path.AppendASCII(kDecodedImagesFilename);
+  std::string file_str;
+  if (!base::ReadFileToString(path, &file_str))
+    return false;
+
+  IPC::Message pickle(file_str.data(), file_str.size());
+  PickleIterator iter(pickle);
+  return IPC::ReadParam(&pickle, &iter, images);
+}
+
+// Read the decoded message catalogs back from the file we saved them to.
+// |extension_path| is the path to the extension we unpacked that wrote the
+// data. Returns true on success.
+bool ReadMessageCatalogsFromFile(const base::FilePath& extension_path,
+                                 base::DictionaryValue* catalogs) {
+  base::FilePath path =
+      extension_path.AppendASCII(kDecodedMessageCatalogsFilename);
+  std::string file_str;
+  if (!base::ReadFileToString(path, &file_str))
+    return false;
+
+  IPC::Message pickle(file_str.data(), file_str.size());
+  PickleIterator iter(pickle);
+  return IPC::ReadParam(&pickle, &iter, catalogs);
+}
+
+}  // namespace
+
+SandboxedUnpacker::SandboxedUnpacker(
+    const base::FilePath& crx_path,
+    Manifest::Location location,
+    int creation_flags,
+    const base::FilePath& extensions_dir,
+    const scoped_refptr<base::SequencedTaskRunner>& unpacker_io_task_runner,
+    SandboxedUnpackerClient* client)
+    : crx_path_(crx_path),
+      client_(client),
+      extensions_dir_(extensions_dir),
+      got_response_(false),
+      location_(location),
+      creation_flags_(creation_flags),
+      unpacker_io_task_runner_(unpacker_io_task_runner) {
+}
+
+bool SandboxedUnpacker::CreateTempDirectory() {
+  CHECK(unpacker_io_task_runner_->RunsTasksOnCurrentThread());
+
+  base::FilePath temp_dir;
+  if (!FindWritableTempLocation(extensions_dir_, &temp_dir)) {
+    ReportFailure(COULD_NOT_GET_TEMP_DIRECTORY,
+                  l10n_util::GetStringFUTF16(
+                      IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                      ASCIIToUTF16("COULD_NOT_GET_TEMP_DIRECTORY")));
+    return false;
+  }
+
+  if (!temp_dir_.CreateUniqueTempDirUnderPath(temp_dir)) {
+    ReportFailure(COULD_NOT_CREATE_TEMP_DIRECTORY,
+                  l10n_util::GetStringFUTF16(
+                      IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                      ASCIIToUTF16("COULD_NOT_CREATE_TEMP_DIRECTORY")));
+    return false;
+  }
+
+  return true;
+}
+
+void SandboxedUnpacker::Start() {
+  // We assume that we are started on the thread that the client wants us to do
+  // file IO on.
+  CHECK(unpacker_io_task_runner_->RunsTasksOnCurrentThread());
+
+  unpack_start_time_ = base::TimeTicks::Now();
+
+  PATH_LENGTH_HISTOGRAM("Extensions.SandboxUnpackInitialCrxPathLength",
+                        crx_path_);
+  if (!CreateTempDirectory())
+    return;  // ReportFailure() already called.
+
+  // Initialize the path that will eventually contain the unpacked extension.
+  extension_root_ = temp_dir_.path().AppendASCII(kTempExtensionName);
+  PATH_LENGTH_HISTOGRAM("Extensions.SandboxUnpackUnpackedCrxPathLength",
+                        extension_root_);
+
+  // Extract the public key and validate the package.
+  if (!ValidateSignature())
+    return;  // ValidateSignature() already reported the error.
+
+  // Copy the crx file into our working directory.
+  base::FilePath temp_crx_path = temp_dir_.path().Append(crx_path_.BaseName());
+  PATH_LENGTH_HISTOGRAM("Extensions.SandboxUnpackTempCrxPathLength",
+                        temp_crx_path);
+
+  if (!base::CopyFile(crx_path_, temp_crx_path)) {
+    // Failed to copy extension file to temporary directory.
+    ReportFailure(
+        FAILED_TO_COPY_EXTENSION_FILE_TO_TEMP_DIRECTORY,
+        l10n_util::GetStringFUTF16(
+            IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+            ASCIIToUTF16("FAILED_TO_COPY_EXTENSION_FILE_TO_TEMP_DIRECTORY")));
+    return;
+  }
+
+  // The utility process will have access to the directory passed to
+  // SandboxedUnpacker.  That directory should not contain a symlink or NTFS
+  // reparse point.  When the path is used, following the link/reparse point
+  // will cause file system access outside the sandbox path, and the sandbox
+  // will deny the operation.
+  base::FilePath link_free_crx_path;
+  if (!base::NormalizeFilePath(temp_crx_path, &link_free_crx_path)) {
+    LOG(ERROR) << "Could not get the normalized path of "
+               << temp_crx_path.value();
+    ReportFailure(COULD_NOT_GET_SANDBOX_FRIENDLY_PATH,
+                  l10n_util::GetStringUTF16(IDS_EXTENSION_UNPACK_FAILED));
+    return;
+  }
+  PATH_LENGTH_HISTOGRAM("Extensions.SandboxUnpackLinkFreeCrxPathLength",
+                        link_free_crx_path);
+
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+                          base::Bind(&SandboxedUnpacker::StartProcessOnIOThread,
+                                     this, link_free_crx_path));
+}
+
+SandboxedUnpacker::~SandboxedUnpacker() {
+}
+
+bool SandboxedUnpacker::OnMessageReceived(const IPC::Message& message) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(SandboxedUnpacker, message)
+  IPC_MESSAGE_HANDLER(ChromeUtilityHostMsg_UnpackExtension_Succeeded,
+                      OnUnpackExtensionSucceeded)
+  IPC_MESSAGE_HANDLER(ChromeUtilityHostMsg_UnpackExtension_Failed,
+                      OnUnpackExtensionFailed)
+  IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
+}
+
+void SandboxedUnpacker::OnProcessCrashed(int exit_code) {
+  // Don't report crashes if they happen after we got a response.
+  if (got_response_)
+    return;
+
+  // Utility process crashed while trying to install.
+  ReportFailure(
+      UTILITY_PROCESS_CRASHED_WHILE_TRYING_TO_INSTALL,
+      l10n_util::GetStringFUTF16(
+          IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+          ASCIIToUTF16("UTILITY_PROCESS_CRASHED_WHILE_TRYING_TO_INSTALL")) +
+          ASCIIToUTF16(". ") +
+          l10n_util::GetStringUTF16(IDS_EXTENSION_INSTALL_PROCESS_CRASHED));
+}
+
+void SandboxedUnpacker::StartProcessOnIOThread(
+    const base::FilePath& temp_crx_path) {
+  UtilityProcessHost* host =
+      UtilityProcessHost::Create(this, unpacker_io_task_runner_.get());
+  // Grant the subprocess access to the entire subdir the extension file is
+  // in, so that it can unpack to that dir.
+  host->SetExposedDir(temp_crx_path.DirName());
+  host->Send(new ChromeUtilityMsg_UnpackExtension(temp_crx_path, extension_id_,
+                                                  location_, creation_flags_));
+}
+
+void SandboxedUnpacker::OnUnpackExtensionSucceeded(
+    const base::DictionaryValue& manifest) {
+  CHECK(unpacker_io_task_runner_->RunsTasksOnCurrentThread());
+  got_response_ = true;
+
+  scoped_ptr<base::DictionaryValue> final_manifest(
+      RewriteManifestFile(manifest));
+  if (!final_manifest)
+    return;
+
+  // Create an extension object that refers to the temporary location the
+  // extension was unpacked to. We use this until the extension is finally
+  // installed. For example, the install UI shows images from inside the
+  // extension.
+
+  // Localize manifest now, so confirm UI gets correct extension name.
+
+  // TODO(rdevlin.cronin): Continue removing std::string errors and replacing
+  // with base::string16
+  std::string utf8_error;
+  if (!extension_l10n_util::LocalizeExtension(
+          extension_root_, final_manifest.get(), &utf8_error)) {
+    ReportFailure(
+        COULD_NOT_LOCALIZE_EXTENSION,
+        l10n_util::GetStringFUTF16(IDS_EXTENSION_PACKAGE_ERROR_MESSAGE,
+                                   base::UTF8ToUTF16(utf8_error)));
+    return;
+  }
+
+  extension_ =
+      Extension::Create(extension_root_, location_, *final_manifest,
+                        Extension::REQUIRE_KEY | creation_flags_, &utf8_error);
+
+  if (!extension_.get()) {
+    ReportFailure(INVALID_MANIFEST,
+                  ASCIIToUTF16("Manifest is invalid: " + utf8_error));
+    return;
+  }
+
+  SkBitmap install_icon;
+  if (!RewriteImageFiles(&install_icon))
+    return;
+
+  if (!RewriteCatalogFiles())
+    return;
+
+  ReportSuccess(manifest, install_icon);
+}
+
+void SandboxedUnpacker::OnUnpackExtensionFailed(const base::string16& error) {
+  CHECK(unpacker_io_task_runner_->RunsTasksOnCurrentThread());
+  got_response_ = true;
+  ReportFailure(
+      UNPACKER_CLIENT_FAILED,
+      l10n_util::GetStringFUTF16(IDS_EXTENSION_PACKAGE_ERROR_MESSAGE, error));
+}
+
+bool SandboxedUnpacker::ValidateSignature() {
+  base::ScopedFILE file(base::OpenFile(crx_path_, "rb"));
+
+  if (!file.get()) {
+// Could not open crx file for reading.
+#if defined(OS_WIN)
+    // On windows, get the error code.
+    uint32 error_code = ::GetLastError();
+    // TODO(skerner): Use this histogram to understand why so many
+    // windows users hit this error.  crbug.com/69693
+
+    // Windows errors are unit32s, but all of likely errors are in
+    // [1, 1000].  See winerror.h for the meaning of specific values.
+    // Clip errors outside the expected range to a single extra value.
+    // If there are errors in that extra bucket, we will know to expand
+    // the range.
+    const uint32 kMaxErrorToSend = 1001;
+    error_code = std::min(error_code, kMaxErrorToSend);
+    UMA_HISTOGRAM_ENUMERATION("Extensions.ErrorCodeFromCrxOpen", error_code,
+                              kMaxErrorToSend);
+#endif
+
+    ReportFailure(
+        CRX_FILE_NOT_READABLE,
+        l10n_util::GetStringFUTF16(IDS_EXTENSION_PACKAGE_ERROR_CODE,
+                                   ASCIIToUTF16("CRX_FILE_NOT_READABLE")));
+    return false;
+  }
+
+  // Read and verify the header.
+  // TODO(erikkay): Yuck.  I'm not a big fan of this kind of code, but it
+  // appears that we don't have any endian/alignment aware serialization
+  // code in the code base.  So for now, this assumes that we're running
+  // on a little endian machine with 4 byte alignment.
+  CrxFile::Header header;
+  size_t len = fread(&header, 1, sizeof(header), file.get());
+  if (len < sizeof(header)) {
+    // Invalid crx header
+    ReportFailure(CRX_HEADER_INVALID, l10n_util::GetStringFUTF16(
+                                          IDS_EXTENSION_PACKAGE_ERROR_CODE,
+                                          ASCIIToUTF16("CRX_HEADER_INVALID")));
+    return false;
+  }
+
+  CrxFile::Error error;
+  scoped_ptr<CrxFile> crx(CrxFile::Parse(header, &error));
+  if (!crx) {
+    switch (error) {
+      case CrxFile::kWrongMagic:
+        ReportFailure(CRX_MAGIC_NUMBER_INVALID,
+                      l10n_util::GetStringFUTF16(
+                          IDS_EXTENSION_PACKAGE_ERROR_CODE,
+                          ASCIIToUTF16("CRX_MAGIC_NUMBER_INVALID")));
+        break;
+      case CrxFile::kInvalidVersion:
+        // Bad version numer
+        ReportFailure(CRX_VERSION_NUMBER_INVALID,
+                      l10n_util::GetStringFUTF16(
+                          IDS_EXTENSION_PACKAGE_ERROR_CODE,
+                          ASCIIToUTF16("CRX_VERSION_NUMBER_INVALID")));
+        break;
+      case CrxFile::kInvalidKeyTooLarge:
+      case CrxFile::kInvalidSignatureTooLarge:
+        // Excessively large key or signature
+        ReportFailure(
+            CRX_EXCESSIVELY_LARGE_KEY_OR_SIGNATURE,
+            l10n_util::GetStringFUTF16(
+                IDS_EXTENSION_PACKAGE_ERROR_CODE,
+                ASCIIToUTF16("CRX_EXCESSIVELY_LARGE_KEY_OR_SIGNATURE")));
+        break;
+      case CrxFile::kInvalidKeyTooSmall:
+        // Key length is zero
+        ReportFailure(
+            CRX_ZERO_KEY_LENGTH,
+            l10n_util::GetStringFUTF16(IDS_EXTENSION_PACKAGE_ERROR_CODE,
+                                       ASCIIToUTF16("CRX_ZERO_KEY_LENGTH")));
+        break;
+      case CrxFile::kInvalidSignatureTooSmall:
+        // Signature length is zero
+        ReportFailure(CRX_ZERO_SIGNATURE_LENGTH,
+                      l10n_util::GetStringFUTF16(
+                          IDS_EXTENSION_PACKAGE_ERROR_CODE,
+                          ASCIIToUTF16("CRX_ZERO_SIGNATURE_LENGTH")));
+        break;
+    }
+    return false;
+  }
+
+  std::vector<uint8> key;
+  key.resize(header.key_size);
+  len = fread(&key.front(), sizeof(uint8), header.key_size, file.get());
+  if (len < header.key_size) {
+    // Invalid public key
+    ReportFailure(
+        CRX_PUBLIC_KEY_INVALID,
+        l10n_util::GetStringFUTF16(IDS_EXTENSION_PACKAGE_ERROR_CODE,
+                                   ASCIIToUTF16("CRX_PUBLIC_KEY_INVALID")));
+    return false;
+  }
+
+  std::vector<uint8> signature;
+  signature.resize(header.signature_size);
+  len = fread(&signature.front(), sizeof(uint8), header.signature_size,
+              file.get());
+  if (len < header.signature_size) {
+    // Invalid signature
+    ReportFailure(
+        CRX_SIGNATURE_INVALID,
+        l10n_util::GetStringFUTF16(IDS_EXTENSION_PACKAGE_ERROR_CODE,
+                                   ASCIIToUTF16("CRX_SIGNATURE_INVALID")));
+    return false;
+  }
+
+  crypto::SignatureVerifier verifier;
+  if (!verifier.VerifyInit(
+          crx_file::kSignatureAlgorithm, sizeof(crx_file::kSignatureAlgorithm),
+          &signature.front(), signature.size(), &key.front(), key.size())) {
+    // Signature verification initialization failed. This is most likely
+    // caused by a public key in the wrong format (should encode algorithm).
+    ReportFailure(
+        CRX_SIGNATURE_VERIFICATION_INITIALIZATION_FAILED,
+        l10n_util::GetStringFUTF16(
+            IDS_EXTENSION_PACKAGE_ERROR_CODE,
+            ASCIIToUTF16("CRX_SIGNATURE_VERIFICATION_INITIALIZATION_FAILED")));
+    return false;
+  }
+
+  unsigned char buf[1 << 12];
+  while ((len = fread(buf, 1, sizeof(buf), file.get())) > 0)
+    verifier.VerifyUpdate(buf, len);
+
+  if (!verifier.VerifyFinal()) {
+    // Signature verification failed
+    ReportFailure(CRX_SIGNATURE_VERIFICATION_FAILED,
+                  l10n_util::GetStringFUTF16(
+                      IDS_EXTENSION_PACKAGE_ERROR_CODE,
+                      ASCIIToUTF16("CRX_SIGNATURE_VERIFICATION_FAILED")));
+    return false;
+  }
+
+  std::string public_key =
+      std::string(reinterpret_cast<char*>(&key.front()), key.size());
+  base::Base64Encode(public_key, &public_key_);
+
+  extension_id_ = crx_file::id_util::GenerateId(public_key);
+
+  return true;
+}
+
+void SandboxedUnpacker::ReportFailure(FailureReason reason,
+                                      const base::string16& error) {
+  UMA_HISTOGRAM_ENUMERATION("Extensions.SandboxUnpackFailureReason", reason,
+                            NUM_FAILURE_REASONS);
+  UMA_HISTOGRAM_TIMES("Extensions.SandboxUnpackFailureTime",
+                      base::TimeTicks::Now() - unpack_start_time_);
+  Cleanup();
+  client_->OnUnpackFailure(error);
+}
+
+void SandboxedUnpacker::ReportSuccess(
+    const base::DictionaryValue& original_manifest,
+    const SkBitmap& install_icon) {
+  UMA_HISTOGRAM_COUNTS("Extensions.SandboxUnpackSuccess", 1);
+
+  RecordSuccessfulUnpackTimeHistograms(
+      crx_path_, base::TimeTicks::Now() - unpack_start_time_);
+
+  // Client takes ownership of temporary directory and extension.
+  client_->OnUnpackSuccess(temp_dir_.Take(), extension_root_,
+                           &original_manifest, extension_.get(), install_icon);
+  extension_ = NULL;
+}
+
+base::DictionaryValue* SandboxedUnpacker::RewriteManifestFile(
+    const base::DictionaryValue& manifest) {
+  // Add the public key extracted earlier to the parsed manifest and overwrite
+  // the original manifest. We do this to ensure the manifest doesn't contain an
+  // exploitable bug that could be used to compromise the browser.
+  scoped_ptr<base::DictionaryValue> final_manifest(manifest.DeepCopy());
+  final_manifest->SetString(manifest_keys::kPublicKey, public_key_);
+
+  std::string manifest_json;
+  JSONStringValueSerializer serializer(&manifest_json);
+  serializer.set_pretty_print(true);
+  if (!serializer.Serialize(*final_manifest)) {
+    // Error serializing manifest.json.
+    ReportFailure(ERROR_SERIALIZING_MANIFEST_JSON,
+                  l10n_util::GetStringFUTF16(
+                      IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                      ASCIIToUTF16("ERROR_SERIALIZING_MANIFEST_JSON")));
+    return NULL;
+  }
+
+  base::FilePath manifest_path = extension_root_.Append(kManifestFilename);
+  int size = base::checked_cast<int>(manifest_json.size());
+  if (base::WriteFile(manifest_path, manifest_json.data(), size) != size) {
+    // Error saving manifest.json.
+    ReportFailure(
+        ERROR_SAVING_MANIFEST_JSON,
+        l10n_util::GetStringFUTF16(IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                                   ASCIIToUTF16("ERROR_SAVING_MANIFEST_JSON")));
+    return NULL;
+  }
+
+  return final_manifest.release();
+}
+
+bool SandboxedUnpacker::RewriteImageFiles(SkBitmap* install_icon) {
+  DecodedImages images;
+  if (!ReadImagesFromFile(temp_dir_.path(), &images)) {
+    // Couldn't read image data from disk.
+    ReportFailure(COULD_NOT_READ_IMAGE_DATA_FROM_DISK,
+                  l10n_util::GetStringFUTF16(
+                      IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                      ASCIIToUTF16("COULD_NOT_READ_IMAGE_DATA_FROM_DISK")));
+    return false;
+  }
+
+  // Delete any images that may be used by the browser.  We're going to write
+  // out our own versions of the parsed images, and we want to make sure the
+  // originals are gone for good.
+  std::set<base::FilePath> image_paths =
+      ExtensionsClient::Get()->GetBrowserImagePaths(extension_.get());
+  if (image_paths.size() != images.size()) {
+    // Decoded images don't match what's in the manifest.
+    ReportFailure(
+        DECODED_IMAGES_DO_NOT_MATCH_THE_MANIFEST,
+        l10n_util::GetStringFUTF16(
+            IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+            ASCIIToUTF16("DECODED_IMAGES_DO_NOT_MATCH_THE_MANIFEST")));
+    return false;
+  }
+
+  for (std::set<base::FilePath>::iterator it = image_paths.begin();
+       it != image_paths.end(); ++it) {
+    base::FilePath path = *it;
+    if (path.IsAbsolute() || path.ReferencesParent()) {
+      // Invalid path for browser image.
+      ReportFailure(INVALID_PATH_FOR_BROWSER_IMAGE,
+                    l10n_util::GetStringFUTF16(
+                        IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                        ASCIIToUTF16("INVALID_PATH_FOR_BROWSER_IMAGE")));
+      return false;
+    }
+    if (!base::DeleteFile(extension_root_.Append(path), false)) {
+      // Error removing old image file.
+      ReportFailure(ERROR_REMOVING_OLD_IMAGE_FILE,
+                    l10n_util::GetStringFUTF16(
+                        IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                        ASCIIToUTF16("ERROR_REMOVING_OLD_IMAGE_FILE")));
+      return false;
+    }
+  }
+
+  const std::string& install_icon_path =
+      IconsInfo::GetIcons(extension_.get())
+          .Get(extension_misc::EXTENSION_ICON_LARGE,
+               ExtensionIconSet::MATCH_BIGGER);
+
+  // Write our parsed images back to disk as well.
+  for (size_t i = 0; i < images.size(); ++i) {
+    if (BrowserThread::GetBlockingPool()->IsShutdownInProgress()) {
+      // Abort package installation if shutdown was initiated, crbug.com/235525
+      ReportFailure(
+          ABORTED_DUE_TO_SHUTDOWN,
+          l10n_util::GetStringFUTF16(IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                                     ASCIIToUTF16("ABORTED_DUE_TO_SHUTDOWN")));
+      return false;
+    }
+
+    const SkBitmap& image = get<0>(images[i]);
+    base::FilePath path_suffix = get<1>(images[i]);
+    if (path_suffix.MaybeAsASCII() == install_icon_path)
+      *install_icon = image;
+
+    if (path_suffix.IsAbsolute() || path_suffix.ReferencesParent()) {
+      // Invalid path for bitmap image.
+      ReportFailure(INVALID_PATH_FOR_BITMAP_IMAGE,
+                    l10n_util::GetStringFUTF16(
+                        IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                        ASCIIToUTF16("INVALID_PATH_FOR_BITMAP_IMAGE")));
+      return false;
+    }
+    base::FilePath path = extension_root_.Append(path_suffix);
+
+    std::vector<unsigned char> image_data;
+    // TODO(mpcomplete): It's lame that we're encoding all images as PNG, even
+    // though they may originally be .jpg, etc.  Figure something out.
+    // http://code.google.com/p/chromium/issues/detail?id=12459
+    if (!gfx::PNGCodec::EncodeBGRASkBitmap(image, false, &image_data)) {
+      // Error re-encoding theme image.
+      ReportFailure(ERROR_RE_ENCODING_THEME_IMAGE,
+                    l10n_util::GetStringFUTF16(
+                        IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                        ASCIIToUTF16("ERROR_RE_ENCODING_THEME_IMAGE")));
+      return false;
+    }
+
+    // Note: we're overwriting existing files that the utility process wrote,
+    // so we can be sure the directory exists.
+    const char* image_data_ptr = reinterpret_cast<const char*>(&image_data[0]);
+    int size = base::checked_cast<int>(image_data.size());
+    if (base::WriteFile(path, image_data_ptr, size) != size) {
+      // Error saving theme image.
+      ReportFailure(
+          ERROR_SAVING_THEME_IMAGE,
+          l10n_util::GetStringFUTF16(IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                                     ASCIIToUTF16("ERROR_SAVING_THEME_IMAGE")));
+      return false;
+    }
+  }
+
+  return true;
+}
+
+bool SandboxedUnpacker::RewriteCatalogFiles() {
+  base::DictionaryValue catalogs;
+  if (!ReadMessageCatalogsFromFile(temp_dir_.path(), &catalogs)) {
+    // Could not read catalog data from disk.
+    ReportFailure(COULD_NOT_READ_CATALOG_DATA_FROM_DISK,
+                  l10n_util::GetStringFUTF16(
+                      IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                      ASCIIToUTF16("COULD_NOT_READ_CATALOG_DATA_FROM_DISK")));
+    return false;
+  }
+
+  // Write our parsed catalogs back to disk.
+  for (base::DictionaryValue::Iterator it(catalogs); !it.IsAtEnd();
+       it.Advance()) {
+    const base::DictionaryValue* catalog = NULL;
+    if (!it.value().GetAsDictionary(&catalog)) {
+      // Invalid catalog data.
+      ReportFailure(
+          INVALID_CATALOG_DATA,
+          l10n_util::GetStringFUTF16(IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                                     ASCIIToUTF16("INVALID_CATALOG_DATA")));
+      return false;
+    }
+
+    base::FilePath relative_path = base::FilePath::FromUTF8Unsafe(it.key());
+    relative_path = relative_path.Append(kMessagesFilename);
+    if (relative_path.IsAbsolute() || relative_path.ReferencesParent()) {
+      // Invalid path for catalog.
+      ReportFailure(
+          INVALID_PATH_FOR_CATALOG,
+          l10n_util::GetStringFUTF16(IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                                     ASCIIToUTF16("INVALID_PATH_FOR_CATALOG")));
+      return false;
+    }
+    base::FilePath path = extension_root_.Append(relative_path);
+
+    std::string catalog_json;
+    JSONStringValueSerializer serializer(&catalog_json);
+    serializer.set_pretty_print(true);
+    if (!serializer.Serialize(*catalog)) {
+      // Error serializing catalog.
+      ReportFailure(ERROR_SERIALIZING_CATALOG,
+                    l10n_util::GetStringFUTF16(
+                        IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                        ASCIIToUTF16("ERROR_SERIALIZING_CATALOG")));
+      return false;
+    }
+
+    // Note: we're overwriting existing files that the utility process read,
+    // so we can be sure the directory exists.
+    int size = base::checked_cast<int>(catalog_json.size());
+    if (base::WriteFile(path, catalog_json.c_str(), size) != size) {
+      // Error saving catalog.
+      ReportFailure(
+          ERROR_SAVING_CATALOG,
+          l10n_util::GetStringFUTF16(IDS_EXTENSION_PACKAGE_INSTALL_ERROR,
+                                     ASCIIToUTF16("ERROR_SAVING_CATALOG")));
+      return false;
+    }
+  }
+
+  return true;
+}
+
+void SandboxedUnpacker::Cleanup() {
+  DCHECK(unpacker_io_task_runner_->RunsTasksOnCurrentThread());
+  if (!temp_dir_.Delete()) {
+    LOG(WARNING) << "Can not delete temp directory at "
+                 << temp_dir_.path().value();
+  }
+}
+
+}  // namespace extensions
diff --git a/extensions/browser/sandboxed_unpacker.h b/extensions/browser/sandboxed_unpacker.h
new file mode 100644
index 0000000..60a5bbd
--- /dev/null
+++ b/extensions/browser/sandboxed_unpacker.h
@@ -0,0 +1,246 @@
+// Copyright (c) 2012 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_EXTENSIONS_SANDBOXED_UNPACKER_H_
+#define CHROME_BROWSER_EXTENSIONS_SANDBOXED_UNPACKER_H_
+
+#include <string>
+
+#include "base/files/file_path.h"
+#include "base/files/scoped_temp_dir.h"
+#include "base/memory/ref_counted.h"
+#include "base/time/time.h"
+#include "content/public/browser/utility_process_host_client.h"
+#include "extensions/common/manifest.h"
+
+class SkBitmap;
+
+namespace base {
+class DictionaryValue;
+class SequencedTaskRunner;
+}
+
+namespace extensions {
+class Extension;
+
+class SandboxedUnpackerClient
+    : public base::RefCountedThreadSafe<SandboxedUnpackerClient> {
+ public:
+  // temp_dir - A temporary directory containing the results of the extension
+  // unpacking. The client is responsible for deleting this directory.
+  //
+  // extension_root - The path to the extension root inside of temp_dir.
+  //
+  // original_manifest - The parsed but unmodified version of the manifest,
+  // with no modifications such as localization, etc.
+  //
+  // extension - The extension that was unpacked. The client is responsible
+  // for deleting this memory.
+  //
+  // install_icon - The icon we will display in the installation UI, if any.
+  virtual void OnUnpackSuccess(const base::FilePath& temp_dir,
+                               const base::FilePath& extension_root,
+                               const base::DictionaryValue* original_manifest,
+                               const Extension* extension,
+                               const SkBitmap& install_icon) = 0;
+  virtual void OnUnpackFailure(const base::string16& error) = 0;
+
+ protected:
+  friend class base::RefCountedThreadSafe<SandboxedUnpackerClient>;
+
+  virtual ~SandboxedUnpackerClient() {}
+};
+
+// SandboxedUnpacker unpacks extensions from the CRX format into a
+// directory. This is done in a sandboxed subprocess to protect the browser
+// process from parsing complex formats like JPEG or JSON from untrusted
+// sources.
+//
+// Unpacking an extension using this class makes minor changes to its source,
+// such as transcoding all images to PNG, parsing all message catalogs
+// and rewriting the manifest JSON. As such, it should not be used when the
+// output is not intended to be given back to the author.
+//
+//
+// Lifetime management:
+//
+// This class is ref-counted by each call it makes to itself on another thread,
+// and by UtilityProcessHost.
+//
+// Additionally, we hold a reference to our own client so that it lives at least
+// long enough to receive the result of unpacking.
+//
+//
+// NOTE: This class should only be used on the file thread.
+class SandboxedUnpacker : public content::UtilityProcessHostClient {
+ public:
+  // Unpacks the extension in |crx_path| into a temporary directory and calls
+  // |client| with the result. If |run_out_of_process| is provided, unpacking
+  // is done in a sandboxed subprocess. Otherwise, it is done in-process.
+  SandboxedUnpacker(
+      const base::FilePath& crx_path,
+      Manifest::Location location,
+      int creation_flags,
+      const base::FilePath& extensions_dir,
+      const scoped_refptr<base::SequencedTaskRunner>& unpacker_io_task_runner,
+      SandboxedUnpackerClient* client);
+
+  // Start unpacking the extension. The client is called with the results.
+  void Start();
+
+ private:
+  class ProcessHostClient;
+
+  // Enumerate all the ways unpacking can fail.  Calls to ReportFailure()
+  // take a failure reason as an argument, and put it in histogram
+  // Extensions.SandboxUnpackFailureReason.
+  enum FailureReason {
+    // SandboxedUnpacker::CreateTempDirectory()
+    COULD_NOT_GET_TEMP_DIRECTORY,
+    COULD_NOT_CREATE_TEMP_DIRECTORY,
+
+    // SandboxedUnpacker::Start()
+    FAILED_TO_COPY_EXTENSION_FILE_TO_TEMP_DIRECTORY,
+    COULD_NOT_GET_SANDBOX_FRIENDLY_PATH,
+
+    // SandboxedUnpacker::OnUnpackExtensionSucceeded()
+    COULD_NOT_LOCALIZE_EXTENSION,
+    INVALID_MANIFEST,
+
+    // SandboxedUnpacker::OnUnpackExtensionFailed()
+    UNPACKER_CLIENT_FAILED,
+
+    // SandboxedUnpacker::OnProcessCrashed()
+    UTILITY_PROCESS_CRASHED_WHILE_TRYING_TO_INSTALL,
+
+    // SandboxedUnpacker::ValidateSignature()
+    CRX_FILE_NOT_READABLE,
+    CRX_HEADER_INVALID,
+    CRX_MAGIC_NUMBER_INVALID,
+    CRX_VERSION_NUMBER_INVALID,
+    CRX_EXCESSIVELY_LARGE_KEY_OR_SIGNATURE,
+    CRX_ZERO_KEY_LENGTH,
+    CRX_ZERO_SIGNATURE_LENGTH,
+    CRX_PUBLIC_KEY_INVALID,
+    CRX_SIGNATURE_INVALID,
+    CRX_SIGNATURE_VERIFICATION_INITIALIZATION_FAILED,
+    CRX_SIGNATURE_VERIFICATION_FAILED,
+
+    // SandboxedUnpacker::RewriteManifestFile()
+    ERROR_SERIALIZING_MANIFEST_JSON,
+    ERROR_SAVING_MANIFEST_JSON,
+
+    // SandboxedUnpacker::RewriteImageFiles()
+    COULD_NOT_READ_IMAGE_DATA_FROM_DISK,
+    DECODED_IMAGES_DO_NOT_MATCH_THE_MANIFEST,
+    INVALID_PATH_FOR_BROWSER_IMAGE,
+    ERROR_REMOVING_OLD_IMAGE_FILE,
+    INVALID_PATH_FOR_BITMAP_IMAGE,
+    ERROR_RE_ENCODING_THEME_IMAGE,
+    ERROR_SAVING_THEME_IMAGE,
+    ABORTED_DUE_TO_SHUTDOWN,
+
+    // SandboxedUnpacker::RewriteCatalogFiles()
+    COULD_NOT_READ_CATALOG_DATA_FROM_DISK,
+    INVALID_CATALOG_DATA,
+    INVALID_PATH_FOR_CATALOG,
+    ERROR_SERIALIZING_CATALOG,
+    ERROR_SAVING_CATALOG,
+
+    NUM_FAILURE_REASONS
+  };
+
+  friend class ProcessHostClient;
+  friend class SandboxedUnpackerTest;
+
+  ~SandboxedUnpacker() override;
+
+  // Set |temp_dir_| as a temporary directory to unpack the extension in.
+  // Return true on success.
+  virtual bool CreateTempDirectory();
+
+  // Validates the signature of the extension and extract the key to
+  // |public_key_|. Returns true if the signature validates, false otherwise.
+  //
+  // NOTE: Having this method here is a bit ugly. This code should really live
+  // in extensions::Unpacker as it is not specific to sandboxed unpacking. It
+  // was put here because we cannot run windows crypto code in the sandbox. But
+  // we could still have this method statically on extensions::Unpacker so that
+  // code just for unpacking is there and code just for sandboxing of unpacking
+  // is here.
+  bool ValidateSignature();
+
+  // Starts the utility process that unpacks our extension.
+  void StartProcessOnIOThread(const base::FilePath& temp_crx_path);
+
+  // UtilityProcessHostClient
+  bool OnMessageReceived(const IPC::Message& message) override;
+  void OnProcessCrashed(int exit_code) override;
+
+  // IPC message handlers.
+  void OnUnpackExtensionSucceeded(const base::DictionaryValue& manifest);
+  void OnUnpackExtensionFailed(const base::string16& error_message);
+
+  void ReportFailure(FailureReason reason, const base::string16& message);
+  void ReportSuccess(const base::DictionaryValue& original_manifest,
+                     const SkBitmap& install_icon);
+
+  // Overwrites original manifest with safe result from utility process.
+  // Returns NULL on error. Caller owns the returned object.
+  base::DictionaryValue* RewriteManifestFile(
+      const base::DictionaryValue& manifest);
+
+  // Overwrites original files with safe results from utility process.
+  // Reports error and returns false if it fails.
+  bool RewriteImageFiles(SkBitmap* install_icon);
+  bool RewriteCatalogFiles();
+
+  // Cleans up temp directory artifacts.
+  void Cleanup();
+
+  // The path to the CRX to unpack.
+  base::FilePath crx_path_;
+
+  // Our client.
+  scoped_refptr<SandboxedUnpackerClient> client_;
+
+  // The Extensions directory inside the profile.
+  base::FilePath extensions_dir_;
+
+  // A temporary directory to use for unpacking.
+  base::ScopedTempDir temp_dir_;
+
+  // The root directory of the unpacked extension. This is a child of temp_dir_.
+  base::FilePath extension_root_;
+
+  // Represents the extension we're unpacking.
+  scoped_refptr<Extension> extension_;
+
+  // Whether we've received a response from the utility process yet.
+  bool got_response_;
+
+  // The public key that was extracted from the CRX header.
+  std::string public_key_;
+
+  // The extension's ID. This will be calculated from the public key in the crx
+  // header.
+  std::string extension_id_;
+
+  // Time at which unpacking started. Used to compute the time unpacking takes.
+  base::TimeTicks unpack_start_time_;
+
+  // Location to use for the unpacked extension.
+  Manifest::Location location_;
+
+  // Creation flags to use for the extension.  These flags will be used
+  // when calling Extenion::Create() by the crx installer.
+  int creation_flags_;
+
+  // Sequenced task runner where file I/O operations will be performed at.
+  scoped_refptr<base::SequencedTaskRunner> unpacker_io_task_runner_;
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_SANDBOXED_UNPACKER_H_
diff --git a/extensions/browser/sandboxed_unpacker_unittest.cc b/extensions/browser/sandboxed_unpacker_unittest.cc
new file mode 100644
index 0000000..7451b28
--- /dev/null
+++ b/extensions/browser/sandboxed_unpacker_unittest.cc
@@ -0,0 +1,120 @@
+// Copyright (c) 2012 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 "base/bind.h"
+#include "base/files/file_util.h"
+#include "base/memory/ref_counted.h"
+#include "base/message_loop/message_loop.h"
+#include "base/path_service.h"
+#include "base/run_loop.h"
+#include "base/strings/string_util.h"
+#include "base/values.h"
+#include "content/public/test/test_browser_thread_bundle.h"
+#include "content/public/test/test_utils.h"
+#include "extensions/browser/extensions_test.h"
+#include "extensions/browser/sandboxed_unpacker.h"
+#include "extensions/common/constants.h"
+#include "extensions/common/extension.h"
+#include "extensions/common/extension_paths.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+
+namespace extensions {
+
+class MockSandboxedUnpackerClient : public SandboxedUnpackerClient {
+ public:
+  void WaitForUnpack() {
+    scoped_refptr<content::MessageLoopRunner> runner =
+        new content::MessageLoopRunner;
+    quit_closure_ = runner->QuitClosure();
+    runner->Run();
+  }
+
+  base::FilePath temp_dir() const { return temp_dir_; }
+
+ private:
+  ~MockSandboxedUnpackerClient() override {}
+
+  void OnUnpackSuccess(const base::FilePath& temp_dir,
+                       const base::FilePath& extension_root,
+                       const base::DictionaryValue* original_manifest,
+                       const Extension* extension,
+                       const SkBitmap& install_icon) override {
+    temp_dir_ = temp_dir;
+    quit_closure_.Run();
+  }
+
+  void OnUnpackFailure(const base::string16& error) override {
+    ASSERT_TRUE(false);
+  }
+
+  base::Closure quit_closure_;
+  base::FilePath temp_dir_;
+};
+
+class SandboxedUnpackerTest : public ExtensionsTest {
+ public:
+  void SetUp() override {
+    ExtensionsTest::SetUp();
+    ASSERT_TRUE(extensions_dir_.CreateUniqueTempDir());
+    browser_threads_.reset(new content::TestBrowserThreadBundle(
+        content::TestBrowserThreadBundle::IO_MAINLOOP));
+    in_process_utility_thread_helper_.reset(
+        new content::InProcessUtilityThreadHelper);
+    // It will delete itself.
+    client_ = new MockSandboxedUnpackerClient;
+  }
+
+  void TearDown() override {
+    // Need to destruct SandboxedUnpacker before the message loop since
+    // it posts a task to it.
+    sandboxed_unpacker_ = NULL;
+    base::RunLoop().RunUntilIdle();
+    ExtensionsTest::TearDown();
+  }
+
+  void SetupUnpacker(const std::string& crx_name) {
+    base::FilePath original_path;
+    ASSERT_TRUE(PathService::Get(extensions::DIR_TEST_DATA, &original_path));
+    original_path = original_path.AppendASCII("unpacker").AppendASCII(crx_name);
+    ASSERT_TRUE(base::PathExists(original_path)) << original_path.value();
+
+    sandboxed_unpacker_ = new SandboxedUnpacker(
+        original_path, Manifest::INTERNAL, Extension::NO_FLAGS,
+        extensions_dir_.path(), base::MessageLoopProxy::current(), client_);
+
+    base::MessageLoopProxy::current()->PostTask(
+        FROM_HERE,
+        base::Bind(&SandboxedUnpacker::Start, sandboxed_unpacker_.get()));
+    client_->WaitForUnpack();
+  }
+
+  base::FilePath GetInstallPath() {
+    return client_->temp_dir().AppendASCII(kTempExtensionName);
+  }
+
+ protected:
+  base::ScopedTempDir extensions_dir_;
+  MockSandboxedUnpackerClient* client_;
+  scoped_refptr<SandboxedUnpacker> sandboxed_unpacker_;
+  scoped_ptr<content::TestBrowserThreadBundle> browser_threads_;
+  scoped_ptr<content::InProcessUtilityThreadHelper>
+      in_process_utility_thread_helper_;
+};
+
+TEST_F(SandboxedUnpackerTest, NoCatalogsSuccess) {
+  SetupUnpacker("no_l10n.crx");
+  // Check that there is no _locales folder.
+  base::FilePath install_path = GetInstallPath().Append(kLocaleFolder);
+  EXPECT_FALSE(base::PathExists(install_path));
+}
+
+TEST_F(SandboxedUnpackerTest, WithCatalogsSuccess) {
+  SetupUnpacker("good_l10n.crx");
+  // Check that there is _locales folder.
+  base::FilePath install_path = GetInstallPath().Append(kLocaleFolder);
+  EXPECT_TRUE(base::PathExists(install_path));
+}
+
+}  // namespace extensions
diff --git a/extensions/common/extension_utility_messages.h b/extensions/common/extension_utility_messages.h
index 123fc98..35e37a3 100644
--- a/extensions/common/extension_utility_messages.h
+++ b/extensions/common/extension_utility_messages.h
@@ -41,6 +41,14 @@ IPC_STRUCT_TRAITS_END()
 IPC_MESSAGE_CONTROL1(ExtensionUtilityMsg_ParseUpdateManifest,
                      std::string /* xml document contents */)
 
+// Tells the utility process to unpack the given extension file in its
+// directory and verify that it is valid.
+IPC_MESSAGE_CONTROL4(ChromeUtilityMsg_UnpackExtension,
+                     base::FilePath /* extension_filename */,
+                     std::string /* extension_id */,
+                     int /* Manifest::Location */,
+                     int /* InitFromValue flags */)
+
 //------------------------------------------------------------------------------
 // Utility process host messages:
 // These are messages from the utility process to the browser.
@@ -54,3 +62,18 @@ IPC_MESSAGE_CONTROL1(ExtensionUtilityHostMsg_ParseUpdateManifest_Succeeded,
 // is a description of what went wrong suitable for logging.
 IPC_MESSAGE_CONTROL1(ExtensionUtilityHostMsg_ParseUpdateManifest_Failed,
                      std::string /* error_message, if any */)
+
+// Reply when the utility process is done unpacking an extension.  |manifest|
+// is the parsed manifest.json file.
+// The unpacker should also have written out files containing the decoded
+// images and message catalogs from the extension. The data is written into a
+// DecodedImages struct into a file named kDecodedImagesFilename in the
+// directory that was passed in. This is done because the data is too large to
+// pass over IPC.
+IPC_MESSAGE_CONTROL1(ChromeUtilityHostMsg_UnpackExtension_Succeeded,
+                     base::DictionaryValue /* manifest */)
+
+// Reply when the utility process has failed while unpacking an extension.
+// |error_message| is a user-displayable explanation of what went wrong.
+IPC_MESSAGE_CONTROL1(ChromeUtilityHostMsg_UnpackExtension_Failed,
+                     base::string16 /* error_message, if any */)
diff --git a/extensions/extensions.gyp b/extensions/extensions.gyp
index 0977c5d..9b7bfbb 100644
--- a/extensions/extensions.gyp
+++ b/extensions/extensions.gyp
@@ -795,6 +795,8 @@
         'browser/renderer_startup_helper.h',
         'browser/runtime_data.cc',
         'browser/runtime_data.h',
+        'browser/sandboxed_unpacker.cc',
+        'browser/sandboxed_unpacker.h',
         'browser/script_execution_observer.h',
         'browser/script_executor.cc',
         'browser/script_executor.h',
@@ -1110,7 +1112,7 @@
         'browser/guest_view/test_guest_view_manager.cc',
         'browser/guest_view/test_guest_view_manager.h',
         'browser/mock_extension_system.cc',
-                                                                                             'browser/mock_extension_system.h',
+        'browser/mock_extension_system.h',
         'browser/test_extension_registry_observer.cc',
         'browser/test_extension_registry_observer.h',
         'browser/test_extensions_browser_client.cc',
@@ -1133,6 +1135,8 @@
         'test/extension_test_message_listener.h',
         'test/result_catcher.cc',
         'test/result_catcher.h',
+        'test/test_content_utility_client.cc',
+        'test/test_content_utility_client.h',
         'test/test_extensions_client.cc',
         'test/test_extensions_client.h',
         'test/test_permission_message_provider.cc',
diff --git a/extensions/extensions_strings.grd b/extensions/extensions_strings.grd
index e4ab2c4..b15ed35 100644
--- a/extensions/extensions_strings.grd
+++ b/extensions/extensions_strings.grd
@@ -440,6 +440,29 @@
         Communicate with cooperating websites
       </message>
 
+      <!-- Install related messages. Please keep alphabetized. -->
+      <message name="IDS_EXTENSION_INSTALL_PROCESS_CRASHED" desc="Error message in case package fails to install because a utility process crashed.">
+        Could not install package because a utility process crashed. Try restarting Chrome and trying again.
+      </message>
+      <message name="IDS_EXTENSION_PACKAGE_ERROR_CODE" desc="Error message in cases where we fail to install the extension because the crx file is invalid. For example, because the crx header or signature is invalid.">
+        Package is invalid: '<ph name="ERROR_CODE">$1<ex>error</ex></ph>'.
+      </message>
+      <message name="IDS_EXTENSION_PACKAGE_ERROR_MESSAGE" desc="The cases where we get an error message string back from some other component. The message might be in English, but these are typically developer errors, and the extension SDK is English.">
+        Package is invalid. Details: '<ph name="ERROR_MESSAGE">$1<ex>error</ex></ph>'.
+      </message>
+      <message name="IDS_EXTENSION_PACKAGE_INSTALL_ERROR" desc="Error message in case package fails to install because of some problem with the filesystem.">
+        Could not install package: '<ph name="ERROR_CODE">$1<ex>error</ex></ph>'
+      </message>
+      <if expr="is_win">
+        <message name="IDS_EXTENSION_UNPACK_FAILED" desc="On windows, it is possible to mount a disk without the root of that disk having a drive letter.  The sandbox does not support this. See crbug/49530 .">
+          Can not unpack extension.  To safely unpack an extension, there must be a path to your profile directory that starts with a drive letter and does not contain a junction, mount point, or symlink.  No such path exists for your profile.
+        </message>
+      </if>
+      <if expr="not is_win">
+        <message name="IDS_EXTENSION_UNPACK_FAILED" desc="">
+          Can not unpack extension.  To safely unpack an extension, there must be a path to your profile directory that does not contain a symlink.  No such path exists for your profile.
+        </message>
+      </if>
     </messages>
   </release>
 </grit>
diff --git a/extensions/extensions_tests.gyp b/extensions/extensions_tests.gyp
index 0f47938..b1f8e85 100644
--- a/extensions/extensions_tests.gyp
+++ b/extensions/extensions_tests.gyp
@@ -90,6 +90,7 @@
         'browser/process_map_unittest.cc',
         'browser/quota_service_unittest.cc',
         'browser/runtime_data_unittest.cc',
+        'browser/sandboxed_unpacker_unittest.cc',
         'browser/value_store/leveldb_value_store_unittest.cc',
         'browser/value_store/testing_value_store_unittest.cc',
         'browser/value_store/value_store_change_unittest.cc',
diff --git a/extensions/test/extensions_unittests_main.cc b/extensions/test/extensions_unittests_main.cc
index 9452f31b..6fde7a3 100644
--- a/extensions/test/extensions_unittests_main.cc
+++ b/extensions/test/extensions_unittests_main.cc
@@ -74,6 +74,7 @@ void ExtensionsTestSuite::Initialize() {
     ExtensionsContentClient content_client;
     RegisterContentSchemes(&content_client);
   }
+  RegisterInProcessThreads();
 
   extensions::RegisterPathProvider();
 
diff --git a/extensions/test/test_content_utility_client.cc b/extensions/test/test_content_utility_client.cc
new file mode 100644
index 0000000..93f907e
--- /dev/null
+++ b/extensions/test/test_content_utility_client.cc
@@ -0,0 +1,24 @@
+// 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 "extensions/test/test_content_utility_client.h"
+
+namespace extensions {
+
+TestContentUtilityClient::TestContentUtilityClient() {
+}
+
+TestContentUtilityClient::~TestContentUtilityClient() {
+}
+
+void TestContentUtilityClient::UtilityThreadStarted() {
+  UtilityHandler::UtilityThreadStarted();
+}
+
+bool TestContentUtilityClient::OnMessageReceived(const IPC::Message& message) {
+  return utility_handler_.OnMessageReceived(message);
+}
+
+
+}  // namespace extensions
diff --git a/extensions/test/test_content_utility_client.h b/extensions/test/test_content_utility_client.h
new file mode 100644
index 0000000..518806a
--- /dev/null
+++ b/extensions/test/test_content_utility_client.h
@@ -0,0 +1,28 @@
+// 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.
+
+#ifndef EXTENSIONS_TEST_TEST_CONTENT_UTILITY_CLIENT_H_
+#define EXTENSIONS_TEST_TEST_CONTENT_UTILITY_CLIENT_H_
+
+#include "content/public/utility/content_utility_client.h"
+#include "extensions/utility/utility_handler.h"
+
+namespace extensions {
+
+class TestContentUtilityClient : public content::ContentUtilityClient {
+ public:
+  TestContentUtilityClient();
+  ~TestContentUtilityClient() override;
+
+  // ContentUtilityClient implementation
+  void UtilityThreadStarted() override;
+  bool OnMessageReceived(const IPC::Message& message) override;
+
+ private:
+  UtilityHandler utility_handler_;
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_TEST_TEST_CONTENT_UTILITY_CLIENT_H_
diff --git a/extensions/utility/utility_handler.cc b/extensions/utility/utility_handler.cc
index 1298933..3add93e 100644
--- a/extensions/utility/utility_handler.cc
+++ b/extensions/utility/utility_handler.cc
@@ -5,11 +5,15 @@
 #include "extensions/utility/utility_handler.h"
 
 #include "base/command_line.h"
+#include "base/files/file_path.h"
 #include "content/public/utility/utility_thread.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/extension_l10n_util.h"
 #include "extensions/common/extension_utility_messages.h"
+#include "extensions/common/extensions_client.h"
+#include "extensions/common/manifest.h"
 #include "extensions/common/update_manifest.h"
+#include "extensions/utility/unpacker.h"
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_message_macros.h"
 #include "ui/base/ui_base_switches.h"
@@ -45,6 +49,7 @@ void UtilityHandler::UtilityThreadStarted() {
 bool UtilityHandler::OnMessageReceived(const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(UtilityHandler, message)
+    IPC_MESSAGE_HANDLER(ChromeUtilityMsg_UnpackExtension, OnUnpackExtension)
     IPC_MESSAGE_HANDLER(ExtensionUtilityMsg_ParseUpdateManifest,
                         OnParseUpdateManifest)
     IPC_MESSAGE_UNHANDLED(handled = false)
@@ -64,4 +69,29 @@ void UtilityHandler::OnParseUpdateManifest(const std::string& xml) {
   ReleaseProcessIfNeeded();
 }
 
+void UtilityHandler::OnUnpackExtension(
+    const base::FilePath& extension_path,
+    const std::string& extension_id,
+    int location,
+    int creation_flags) {
+  CHECK_GT(location, Manifest::INVALID_LOCATION);
+  CHECK_LT(location, Manifest::NUM_LOCATIONS);
+  DCHECK(ExtensionsClient::Get());
+  Unpacker unpacker(extension_path,
+                    extension_id,
+                    static_cast<Manifest::Location>(location),
+                    creation_flags);
+  if (unpacker.Run() && unpacker.DumpImagesToFile() &&
+      unpacker.DumpMessageCatalogsToFile()) {
+    Send(new ChromeUtilityHostMsg_UnpackExtension_Succeeded(
+        *unpacker.parsed_manifest()));
+  } else {
+    Send(new ChromeUtilityHostMsg_UnpackExtension_Failed(
+        unpacker.error_message()));
+  }
+
+  ReleaseProcessIfNeeded();
+}
+
+
 }  // namespace extensions
diff --git a/extensions/utility/utility_handler.h b/extensions/utility/utility_handler.h
index 0ae31ec..89a81d6 100644
--- a/extensions/utility/utility_handler.h
+++ b/extensions/utility/utility_handler.h
@@ -7,8 +7,13 @@
 
 #include <string>
 
+#include "base/callback.h"
 #include "base/macros.h"
 
+namespace base {
+class FilePath;
+}
+
 namespace IPC {
 class Message;
 }
@@ -28,6 +33,9 @@ class UtilityHandler {
  private:
   // IPC message handlers.
   void OnParseUpdateManifest(const std::string& xml);
+  void OnUnpackExtension(const base::FilePath& extension_path,
+                         const std::string& extension_id,
+                         int location, int creation_flags);
 
   DISALLOW_COPY_AND_ASSIGN(UtilityHandler);
 };