Introduce FastShowPickler which will be used for app list cold start.

chrome/browser/ui/app_list/fast_show_pickler.cc

+// Copyright 2013 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/ui/app_list/fast_show_pickler.h"
+

[benwells, 2013/08/29 04:49:28]

Nit: extra blank line.

[koz (OOO until 15th September), 2013/08/30 00:44:50]

Done.

+
+namespace {
+
+using app_list::AppListItemModel;
+using app_list::AppListModel;
+
+// These have the same meaning as SkBitmap::Config. Reproduced here to insure
+// against their value changing in Skia. If the order of these changes kVersion
+// should be incremented.
+enum ImageFormat {
+  NONE,
+  A1,
+  A8,
+  INDEX_8,
+  RGB_565,
+  ARGB_4444,
+  ARGB_8888,
+};
+
+bool FormatToConfig(ImageFormat format, SkBitmap::Config* out) {
+  switch (format) {
+    case NONE:
+      *out = SkBitmap::kNo_Config;
+      break;
+    case A1:
+      *out = SkBitmap::kA1_Config;
+      break;
+    case A8:
+      *out = SkBitmap::kA8_Config;
+      break;
+    case INDEX_8:
+      *out = SkBitmap::kIndex8_Config;
+      break;
+    case RGB_565:
+      *out = SkBitmap::kRGB_565_Config;
+      break;
+    case ARGB_4444:
+      *out = SkBitmap::kARGB_4444_Config;
+      break;
+    case ARGB_8888:
+      *out = SkBitmap::kARGB_8888_Config;
+      break;
+    default: return false;
+  }
+  return true;
+}
+
+bool ConfigToFormat(SkBitmap::Config config, ImageFormat* out) {
+  switch (config) {
+    case SkBitmap::kNo_Config:
+      *out = NONE;
+      break;
+    case SkBitmap::kA1_Config:
+      *out = A1;
+      break;
+    case SkBitmap::kA8_Config:
+      *out = A8;
+      break;
+    case SkBitmap::kIndex8_Config:
+      *out = INDEX_8;
+      break;
+    case SkBitmap::kRGB_565_Config:
+      *out = RGB_565;
+      break;
+    case SkBitmap::kARGB_4444_Config:
+      *out = ARGB_4444;
+      break;
+    case SkBitmap::kARGB_8888_Config:
+      *out = ARGB_8888;
+      break;
+    default: return false;
+  }
+  return true;
+}
+
+bool PickleImage(Pickle* pickle, const gfx::ImageSkia& image) {
+  std::vector<gfx::ImageSkiaRep> reps(image.image_reps());

[xiyuan, 2013/08/29 16:52:11]

I just thought of potential problem. ExtensionAppItem uses extensions::IconImage
for its icon. IconImage is lazily loaded. It only loads the image when
GetRepresentation of its exposed ImageSkia is called (during paint or called
explicitly as the preload).

We probably need to force the icons to be loaded before the pickling code.
Otherwise, we probably only persist the icons of the visible page.

[koz (OOO until 15th September), 2013/08/30 00:44:50]

I plan on handling that in a higher layer. There will be a service that listens
to changes in the AppListModel and schedules pickling to occur when necessary,
an icon loading or changing will prompt a re-pickle.

+  pickle->WriteInt(static_cast<int>(reps.size()));
+  for (std::vector<gfx::ImageSkiaRep>::const_iterator it = reps.begin();
+       it != reps.end(); ++it) {
+    pickle->WriteInt(static_cast<int>(it->scale_factor()));
+    pickle->WriteInt(it->pixel_width());
+    pickle->WriteInt(it->pixel_height());
+    ImageFormat format = NONE;
+    if (!ConfigToFormat(it->sk_bitmap().getConfig(), &format))
+      return false;
+    pickle->WriteInt(static_cast<int>(format));
+    int size = static_cast<int>(it->sk_bitmap().getSafeSize());
+    pickle->WriteInt(size);
+    SkBitmap bitmap = it->sk_bitmap();
+    SkAutoLockPixels lock(bitmap);
+    pickle->WriteBytes(bitmap.getPixels(), size);
+  }
+  return true;
+}
+
+gfx::ImageSkia UnpickleImage(PickleIterator* it) {
+  int rep_count = 0;
+  if (!it->ReadInt(&rep_count))
+    return gfx::ImageSkia();
+
+  gfx::ImageSkia result;
+  for (int i = 0; i < rep_count; ++i) {
+    int scale_factor = 0;
+    if (!it->ReadInt(&scale_factor))
+      return gfx::ImageSkia();
+
+    int width = 0;
+    if (!it->ReadInt(&width))
+      return gfx::ImageSkia();
+
+    int height = 0;
+    if (!it->ReadInt(&height))
+      return gfx::ImageSkia();
+
+    int format_int = 0;
+    if (!it->ReadInt(&format_int))
+      return gfx::ImageSkia();
+    ImageFormat format = static_cast<ImageFormat>(format_int);
+    SkBitmap::Config config = SkBitmap::kNo_Config;
+    if (!FormatToConfig(format, &config))
+      return gfx::ImageSkia();
+
+    int size = 0;
+    if (!it->ReadInt(&size))
+      return gfx::ImageSkia();
+
+    const char* pixels = NULL;
+    if (!it->ReadBytes(&pixels, size))
+      return gfx::ImageSkia();
+
+    SkBitmap bitmap;
+    bitmap.setConfig(static_cast<SkBitmap::Config>(config), width, height);
+    if (!bitmap.allocPixels())
+      return gfx::ImageSkia();
+    {
+      SkAutoLockPixels lock(bitmap);
+      memcpy(bitmap.getPixels(), pixels, bitmap.getSize());
+    }
+    result.AddRepresentation(
+        gfx::ImageSkiaRep(bitmap, static_cast<ui::ScaleFactor>(scale_factor)));
+  }
+
+  return result;
+}
+
+scoped_ptr<AppListItemModel> UnpickleAppListItemModel(PickleIterator* it) {
+  scoped_ptr<AppListItemModel> result(new AppListItemModel);
+  std::string id;
+  if (!it->ReadString(&id))
+    return scoped_ptr<AppListItemModel>();
+  result->set_app_id(id);
+  std::string title;
+  if (!it->ReadString(&title))
+    return scoped_ptr<AppListItemModel>();
+  result->SetTitle(title);
+  bool has_shadow = false;
+  if (!it->ReadBool(&has_shadow))
+    return scoped_ptr<AppListItemModel>();
+  gfx::ImageSkia icon = UnpickleImage(it);

[benwells, 2013/08/29 04:49:28]

Should you check icon.empty (or whatever the call is)? Error handling seems to
be covered for all other things that could go wrong.

[koz (OOO until 15th September), 2013/08/30 00:44:50]

Ah, good point. gfx::ImageSkia() is a valid value so I can't use it as a
sentinel anyway. I've changed this function to use an out param.

+  result->SetIcon(icon, has_shadow);
+  return result.Pass();
+}
+
+
+bool PickleAppListItemModel(Pickle* pickle, AppListItemModel* item) {
+  if (!pickle->WriteString(item->app_id()))
+    return false;
+  if (!pickle->WriteString(item->title()))
+    return false;
+  if (!pickle->WriteBool(item->has_shadow()))
+    return false;
+  if (!PickleImage(pickle, item->icon()))
+    return false;
+  return true;
+}
+
+void CopyOverItem(AppListItemModel* src_item, AppListItemModel* dest_item) {
+  dest_item->set_app_id(src_item->app_id());
+  dest_item->SetTitle(src_item->title());
+  dest_item->SetIcon(src_item->icon(), src_item->has_shadow());
+}
+
+}  // namespace
+
+// The version of the pickle format defined here. This needs to be incremented
+// whenever this format is changed so new clients can invalidate old versions.
+const int FastShowPickler::kVersion = 1;
+
+scoped_ptr<Pickle> FastShowPickler::PickleAppListModelForFastShow(
+    AppListModel* model) {
+  scoped_ptr<Pickle> result(new Pickle);
+  if (!result->WriteInt(kVersion))
+    return scoped_ptr<Pickle>();
+  if (!result->WriteInt((int) model->apps()->item_count()))

[benwells, 2013/08/29 04:49:28]

Nit: If it was me I'd swap the item_count and signed_in. item_count just before
the list of items feels better.

[koz (OOO until 15th September), 2013/08/30 00:44:50]

Done.

+    return scoped_ptr<Pickle>();
+  if (!result->WriteBool(model->signed_in()))
+    return scoped_ptr<Pickle>();
+  for (size_t i = 0; i < model->apps()->item_count(); ++i) {
+    if (!PickleAppListItemModel(result.get(), model->apps()->GetItemAt(i)))
+      return scoped_ptr<Pickle>();
+  }
+  return result.Pass();
+}
+
+void FastShowPickler::CopyOver(AppListModel* src, AppListModel* dest) {
+  dest->apps()->DeleteAll();
+  for (size_t i = 0; i < src->apps()->item_count(); i++) {
+    AppListItemModel* src_item = src->apps()->GetItemAt(i);
+    AppListItemModel* dest_item = new AppListItemModel;
+    CopyOverItem(src_item, dest_item);
+    dest->apps()->Add(dest_item);
+  }
+}
+
+scoped_ptr<AppListModel>
+FastShowPickler::UnpickleAppListModelForFastShow(Pickle* pickle) {
+  PickleIterator it(*pickle);
+  int read_version = 0;
+  if (!it.ReadInt(&read_version))
+    return scoped_ptr<AppListModel>();
+  if (read_version != kVersion)
+    return scoped_ptr<AppListModel>();
+  int app_count = 0;
+  if (!it.ReadInt(&app_count))
+    return scoped_ptr<AppListModel>();
+  bool signed_in = false;
+  if (!it.ReadBool(&signed_in))
+    return scoped_ptr<AppListModel>();
+
+  scoped_ptr<AppListModel> model(new AppListModel);
+  for (int i = 0; i < app_count; ++i) {
+    scoped_ptr<AppListItemModel> item(UnpickleAppListItemModel(&it).Pass());
+    if (!item)
+      return scoped_ptr<AppListModel>();
+    model->apps()->Add(item.release());
+  }
+
+  return model.Pass();
+}