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

content/app/content_main_runner.cc

Index: content/app/content_main_runner.cc
diff --git a/content/app/content_main_runner.cc b/content/app/content_main_runner.cc
index 279536b09b983deec9ae5f22856e5c0bbb72f83a..2382700a86973a5db37c5073797fcc2be7b8c83a 100644
--- a/content/app/content_main_runner.cc
+++ b/content/app/content_main_runner.cc
@@ -51,6 +51,10 @@
 #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
@@ -711,7 +715,13 @@ class ContentMainRunnerImpl : public ContentMainRunner {
 
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
-#if !defined(OS_ANDROID)
+#if defined(OS_ANDROID)
+    // Map V8 data from within .apk.
+    CHECK(base::android::RegisterApkAssetWithGlobalDescriptors(
+       kV8NativesDataDescriptor, gin::V8Initializer::kNativesFileName));

[Yaron, 2015/05/25 18:56:44]

Isn't this introducing new blocking IO on the main thread? I believe this used
to happen on the process launcher thread when we grab the fd to forward to child
process

+    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

[Yaron, 2015/05/25 18:56:44]

update

     // ChildProcessService::InternalInitChildProcess, otherwise set them here.
@@ -725,7 +735,7 @@ class ContentMainRunnerImpl : public ContentMainRunner {
           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) {