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

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index f93dc783d6fd234fbcd4365e6d51bd3bca3cd561..c37f2da22839b104e8feb05cce1a42b03c1e92bb 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -123,7 +123,6 @@
 #include "content/public/common/service_registry.h"
 #include "content/public/common/url_utils.h"
 #include "content/public/common/web_preferences.h"
-#include "gin/v8_initializer.h"
 #include "net/base/mime_util.h"
 #include "net/cookies/canonical_cookie.h"
 #include "net/cookies/cookie_options.h"
@@ -608,10 +607,6 @@ namespace chrome {
 
 ChromeContentBrowserClient::ChromeContentBrowserClient()
     :
-#if defined(OS_POSIX) && !defined(OS_MACOSX)
-      v8_natives_fd_(-1),
-      v8_snapshot_fd_(-1),
-#endif  // OS_POSIX && !OS_MACOSX
       weak_factory_(this) {
 #if defined(ENABLE_PLUGINS)
   for (size_t i = 0; i < arraysize(kPredefinedAllowedDevChannelOrigins); ++i)
@@ -1187,13 +1182,11 @@ void ChromeContentBrowserClient::AppendMappedFileCommandLineSwitches(
   std::string process_type =
       command_line->GetSwitchValueASCII(switches::kProcessType);
   if (process_type != switches::kZygoteProcess) {
-    // We want to pass the natives by fd because after an update the file may
-    // be updated, but we want the newly launched renderers to get the old one,
-    // opened by the browser when it started.
-    DCHECK(natives_fd_exists());
+    DCHECK(v8_files_.natives_fd.is_valid());
     command_line->AppendSwitch(::switches::kV8NativesPassedByFD);
-    if (snapshot_fd_exists())
+    if (v8_files_.snapshot_fd.is_valid()) {
       command_line->AppendSwitch(::switches::kV8SnapshotPassedByFD);
+    }
   }
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
 #endif  // OS_POSIX && !OS_MACOSX
@@ -2247,21 +2240,22 @@ void ChromeContentBrowserClient::GetAdditionalMappedFilesForChildProcess(
 #endif
     ) {
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
-  if (!natives_fd_exists()) {
-    int v8_natives_fd = -1;
-    int v8_snapshot_fd = -1;
-    if (gin::V8Initializer::OpenV8FilesForChildProcesses(&v8_natives_fd,
-                                                         &v8_snapshot_fd)) {
-      v8_natives_fd_.reset(v8_natives_fd);
-      v8_snapshot_fd_.reset(v8_snapshot_fd);
-    }
+  if (!v8_files_.natives_fd.is_valid()) {
+    gin::V8Initializer::OpenV8FilesForChildProcesses(&v8_files_);
+  }
+  DCHECK(v8_files_.natives_fd.is_valid());
+  mappings->Share(kV8NativesDataDescriptor, v8_files_.natives_fd.get());
+#if defined(OS_ANDROID)
+  regions->insert(
+      std::make_pair(kV8NativesDataDescriptor, v8_files_.natives_region));
+#endif
+  if (v8_files_.snapshot_fd.is_valid()) {
+    mappings->Share(kV8SnapshotDataDescriptor, v8_files_.snapshot_fd.get());
+#if defined(OS_ANDROID)
+    regions->insert(
+        std::make_pair(kV8SnapshotDataDescriptor, v8_files_.snapshot_region));
+#endif
   }
-  // V8 can't start up without the source of the natives, but it can
-  // start up (slower) without the snapshot.
-  DCHECK(natives_fd_exists());
-  mappings->Share(kV8NativesDataDescriptor, v8_natives_fd_.get());
-  if (snapshot_fd_exists())
-    mappings->Share(kV8SnapshotDataDescriptor, v8_snapshot_fd_.get());
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
 
 #if defined(OS_ANDROID)