Allow startup with missing V8 snapshot file.

content/shell/browser/shell_content_browser_client.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 "content/shell/browser/shell_content_browser_client.h"
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/files/file.h"
 #include "base/files/file_util.h"
@@ skipping 196 matching lines @@
 }
 
 void ShellContentBrowserClient::AppendExtraCommandLineSwitches(
     base::CommandLine* command_line,
     int child_process_id) {
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
   std::string process_type =
       command_line->GetSwitchValueASCII(switches::kProcessType);
   if (process_type != switches::kZygoteProcess) {
-    command_line->AppendSwitch(::switches::kV8NativesPassedByFD);
-    command_line->AppendSwitch(::switches::kV8SnapshotPassedByFD);
+    if (natives_fd_exists()) {
+      command_line->AppendSwitch(::switches::kV8NativesPassedByFD);
+    }
+    if (snapshot_fd_exists()) {
+      command_line->AppendSwitch(::switches::kV8SnapshotPassedByFD);
+    }
   }
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
 #endif  // OS_POSIX && !OS_MACOSX
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kRunLayoutTest))
     command_line->AppendSwitch(switches::kRunLayoutTest);
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnableFontAntialiasing))
     command_line->AppendSwitch(switches::kEnableFontAntialiasing);
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
@@ skipping 107 matching lines @@
                                       nullptr,
                                       gfx::Size())->web_contents());
 }
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
 void ShellContentBrowserClient::GetAdditionalMappedFilesForChildProcess(
     const base::CommandLine& command_line,
     int child_process_id,
     FileDescriptorInfo* mappings) {
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
-  if (v8_natives_fd_.get() == -1 || v8_snapshot_fd_.get() == -1) {
+  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);
     }
   }
-  DCHECK(v8_natives_fd_.get() != -1 && v8_snapshot_fd_.get() != -1);
+  // V8 can't start up without the source of the natives, but it can
+  // start up (slower) without the snapshot.

[rmcilroy, 2015/06/02 15:20:27]

Can you add this comment to all ContentBrowserClient subclasses please.

[Erik Corry Chromium.org, 2015/06/04 11:40:40]

Done.

+  DCHECK(natives_fd_exists());
   mappings->Share(kV8NativesDataDescriptor, v8_natives_fd_.get());
   mappings->Share(kV8SnapshotDataDescriptor, v8_snapshot_fd_.get());
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
 
 #if defined(OS_ANDROID)
   int flags = base::File::FLAG_OPEN | base::File::FLAG_READ;
   base::FilePath pak_file;
   bool r = PathService::Get(base::DIR_ANDROID_APP_DATA, &pak_file);
   CHECK(r);
   pak_file = pak_file.Append(FILE_PATH_LITERAL("paks"));
@@ skipping 59 matching lines @@
 ShellBrowserContext*
 ShellContentBrowserClient::ShellBrowserContextForBrowserContext(
     BrowserContext* content_browser_context) {
   if (content_browser_context == browser_context())
     return browser_context();
   DCHECK_EQ(content_browser_context, off_the_record_browser_context());
   return off_the_record_browser_context();
 }
 
 }  // namespace content