Allow startup with missing V8 snapshot file.

chromecast/browser/cast_content_browser_client.cc

Index: chromecast/browser/cast_content_browser_client.cc
diff --git a/chromecast/browser/cast_content_browser_client.cc b/chromecast/browser/cast_content_browser_client.cc
index e385d963ace8039ba67ad84f28644afdcd444b2e..2f38b12273c1593de866e13009d3b407c94ddb37 100644
--- a/chromecast/browser/cast_content_browser_client.cc
+++ b/chromecast/browser/cast_content_browser_client.cc
@@ -146,21 +146,28 @@ bool CastContentBrowserClient::IsHandledURL(const GURL& url) {
   return false;
 }
 
-void CastContentBrowserClient::AppendExtraCommandLineSwitches(
-    base::CommandLine* command_line,
-    int child_process_id) {
-
+void CastContentBrowserClient::AppendMappedFileCommandLineSwitches(
+    base::CommandLine* command_line) {
   std::string process_type =
       command_line->GetSwitchValueNative(switches::kProcessType);
-  base::CommandLine* browser_command_line =
-      base::CommandLine::ForCurrentProcess();
 
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
   if (process_type != switches::kZygoteProcess) {
+    DCHECK(natives_fd_exists());
     command_line->AppendSwitch(::switches::kV8NativesPassedByFD);
-    command_line->AppendSwitch(::switches::kV8SnapshotPassedByFD);
+    if (snapshot_fd_exists())
+      command_line->AppendSwitch(::switches::kV8SnapshotPassedByFD);
   }
+}
+
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
+void CastContentBrowserClient::AppendExtraCommandLineSwitches(
+    base::CommandLine* command_line,
+    int child_process_id) {
+  std::string process_type =
+      command_line->GetSwitchValueNative(switches::kProcessType);
+  base::CommandLine* browser_command_line =
+      base::CommandLine::ForCurrentProcess();
 
   // IsCrashReporterEnabled() is set when InitCrashReporter() is called, and
   // controlled by GetBreakpadClient()->EnableBreakpadForProcess(), therefore
@@ -316,7 +323,7 @@ void CastContentBrowserClient::GetAdditionalMappedFilesForChildProcess(
     int child_process_id,
     content::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,
@@ -325,7 +332,9 @@ void CastContentBrowserClient::GetAdditionalMappedFilesForChildProcess(
       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.
+  DCHECK(natives_fd_exists());
   mappings->Share(kV8NativesDataDescriptor, v8_natives_fd_.get());
   mappings->Share(kV8SnapshotDataDescriptor, v8_snapshot_fd_.get());
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA