Support snapshots in sky_shell (again)

sky/shell/linux/main.cc

Index: sky/shell/linux/main.cc
diff --git a/sky/shell/linux/main.cc b/sky/shell/linux/main.cc
index 56fd84f5ae306e3510adf74ae1182c65802ac9e0..b40223d582d6901c199001e091642ae33c6bc8f6 100644
--- a/sky/shell/linux/main.cc
+++ b/sky/shell/linux/main.cc
@@ -2,23 +2,37 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <iostream>
+
 #include "base/at_exit.h"
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/command_line.h"
+#include "base/files/file_path.h"
 #include "base/i18n/icu_util.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
+#include "base/threading/worker_pool.h"
+#include "mojo/common/data_pipe_utils.h"
 #include "sky/shell/platform_view.h"
 #include "sky/shell/service_provider.h"
 #include "sky/shell/shell.h"
 #include "sky/shell/shell_view.h"
+#include "sky/shell/switches.h"
 
 namespace sky {
 namespace shell {
+namespace {
+
+void Ignored(bool) {
+}
 
-const char kMain[] = "main";
-const char kPackageRoot[] = "package-root";
+void Usage() {
+  std::cerr << "Usage: sky_shell"
+            << " [--" << switches::kPackageRoot << "]"
+            << " [--" << switches::kSnapshot << "]"
+            << " <sky-app>" << std::endl;
+}
 
 void Init() {
   Shell::Init(make_scoped_ptr(new ServiceProviderContext(
@@ -32,12 +46,31 @@ void Init() {
 
   base::CommandLine& command_line = *base::CommandLine::ForCurrentProcess();
 
-  std::string main = command_line.GetSwitchValueASCII(kMain);
-  std::string package_root = command_line.GetSwitchValueASCII(kPackageRoot);
+  std::string main = command_line.GetArgs()[0];
+  if (command_line.HasSwitch(switches::kSnapshot)) {
+    base::FilePath snapshot =
+        command_line.GetSwitchValuePath(switches::kSnapshot);
+    mojo::DataPipe pipe;
+    viewport_observer->RunFromSnapshot(main, pipe.consumer_handle.Pass());
+    scoped_refptr<base::TaskRunner> runner =
+        base::WorkerPool::GetTaskRunner(true);
+    mojo::common::CopyFromFile(snapshot, pipe.producer_handle.Pass(), 0,
+                               runner.get(), base::Bind(&Ignored));
+    return;
+  }
 
-  viewport_observer->RunFromFile(main, package_root);
+  if (command_line.HasSwitch(switches::kPackageRoot)) {
+    std::string package_root =
+        command_line.GetSwitchValueASCII(switches::kPackageRoot);
+    viewport_observer->RunFromFile(main, package_root);
+    return;
+  }
+
+  std::cerr << "One of --" << switches::kPackageRoot << " or --"
+            << switches::kSnapshot << " is required." << std::endl;
 }
 
+}  // namespace
 } // namespace shell
 } // namespace sky
 
@@ -45,6 +78,14 @@ int main(int argc, const char* argv[]) {
   base::AtExitManager exit_manager;
   base::CommandLine::Init(argc, argv);
 
+  base::CommandLine& command_line = *base::CommandLine::ForCurrentProcess();
+
+  if (command_line.HasSwitch(sky::shell::switches::kHelp) ||
+      command_line.GetArgs().empty()) {
+    sky::shell::Usage();
+    return 0;
+  }
+
   base::MessageLoop message_loop;
 
   base::i18n::InitializeICU();