Load v8 snapshots directly from APK (and store them uncompressed)

content/app/content_main_runner.cc

 // 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 "content/public/app/content_main_runner.h"
 
 #include <stdlib.h>
 
 #include "base/allocator/allocator_extension.h"
 #include "base/at_exit.h"
@@ skipping 33 matching lines @@
 #include "content/renderer/in_process_renderer_thread.h"
 #include "content/utility/in_process_utility_thread.h"
 #include "crypto/nss_util.h"
 #include "ipc/ipc_descriptors.h"
 #include "ipc/ipc_switches.h"
 #include "media/base/media.h"
 #include "sandbox/win/src/sandbox_types.h"
 #include "ui/base/ui_base_paths.h"
 #include "ui/base/ui_base_switches.h"
 
+#if defined(OS_ANDROID)
+#include "base/android/apk_assets.h"
+#endif
+
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
 #include "gin/v8_initializer.h"
 #endif
 
 #if defined(USE_TCMALLOC)
 #include "third_party/tcmalloc/chromium/src/gperftools/malloc_extension.h"
 #if defined(TYPE_PROFILING)
 #include "base/allocator/type_profiler.h"
 #include "base/allocator/type_profiler_tcmalloc.h"
 #endif
@@ skipping 640 matching lines @@
       CHECK(base::i18n::InitializeICU());
     }
 #else
     CHECK(base::i18n::InitializeICU());
 #endif  // OS_ANDROID
 
     base::StatisticsRecorder::Initialize();
 
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
-#if !defined(OS_ANDROID)
+#if defined(OS_ANDROID)
+    // The fds are already mapped in the case of Android WebView.

[rmcilroy, 2015/05/26 09:15:14]

Webview? Please update the comment.

Also, where have you added the code to do this pre-mapping? On Android Webview
this is done with AwAssets::RegisterAssetWithGlobalDescriptors [1], but I don't
see you doing anything similar here.

[1]
https://cs.corp.google.com/#clankium/src/android_webview/lib/main/aw_main_del...

+    if (g_fds->MaybeGet(kV8NativesDataDescriptor) == -1) {

[rmcilroy, 2015/05/26 09:15:14]

Please use the switches::kV8NativesPassedByFD and 
switches::kV8SnapshotPassedByFD and reuse the code below (you will need to
ensure you set the switches correctly). Otherwise this will cause issues with
Erik's on-demand snapshot generation where the kSnapshotFileName might not be
already mapped when the renderer starts depending on whether it has been
generated yet or not.

+      // Map V8 data from within .apk.
+      CHECK(base::android::RegisterApkAssetWithGlobalDescriptors(
+         kV8NativesDataDescriptor, gin::V8Initializer::kNativesFileName));
+      CHECK(base::android::RegisterApkAssetWithGlobalDescriptors(
+         kV8SnapshotDataDescriptor, gin::V8Initializer::kSnapshotFileName));
+    }
+#else
     // kV8NativesDataDescriptor and kV8SnapshotDataDescriptor could be shared
     // with child processes via file descriptors. On Android they are set in
     // ChildProcessService::InternalInitChildProcess, otherwise set them here.
     if (command_line.HasSwitch(switches::kV8NativesPassedByFD)) {
       g_fds->Set(
           kV8NativesDataDescriptor,
           kV8NativesDataDescriptor + base::GlobalDescriptors::kBaseDescriptor);
     }
     if (command_line.HasSwitch(switches::kV8SnapshotPassedByFD)) {
       g_fds->Set(
           kV8SnapshotDataDescriptor,
           kV8SnapshotDataDescriptor + base::GlobalDescriptors::kBaseDescriptor);
     }
-#endif  // !OS_ANDROID
+#endif  // OS_ANDROID
     int v8_natives_fd = g_fds->MaybeGet(kV8NativesDataDescriptor);
     int v8_snapshot_fd = g_fds->MaybeGet(kV8SnapshotDataDescriptor);
     if (v8_natives_fd != -1 && v8_snapshot_fd != -1) {
       auto v8_natives_region = g_fds->GetRegion(kV8NativesDataDescriptor);
       auto v8_snapshot_region = g_fds->GetRegion(kV8SnapshotDataDescriptor);
       CHECK(gin::V8Initializer::LoadV8SnapshotFromFD(
           v8_natives_fd, v8_natives_region.offset, v8_natives_region.size,
           v8_snapshot_fd, v8_snapshot_region.offset, v8_snapshot_region.size));
     } else {
       CHECK(gin::V8Initializer::LoadV8Snapshot());
@@ skipping 108 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(ContentMainRunnerImpl);
 };
 
 // static
 ContentMainRunner* ContentMainRunner::Create() {
   return new ContentMainRunnerImpl();
 }
 
 }  // namespace content