Introduce background Download process to android

content/browser/android/child_process_launcher_android.cc

Index: content/browser/android/child_process_launcher_android.cc
diff --git a/content/browser/android/child_process_launcher_android.cc b/content/browser/android/child_process_launcher_android.cc
index 471ce31d91c728f70f7430c8ec2827272e183722..f6b04e19f5377c47ab5d837d37ff7ab5044f9dd6 100644
--- a/content/browser/android/child_process_launcher_android.cc
+++ b/content/browser/android/child_process_launcher_android.cc
@@ -13,12 +13,16 @@
 #include "base/android/jni_array.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
+#include "content/browser/file_descriptor_info_impl.h"
 #include "content/browser/frame_host/render_frame_host_impl.h"
 #include "content/browser/media/android/browser_media_player_manager.h"
 #include "content/browser/media/android/media_web_contents_observer_android.h"
 #include "content/browser/web_contents/web_contents_impl.h"
+#include "content/common/child_process_host_impl.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/browser/content_browser_client.h"
 #include "content/public/browser/render_process_host.h"
+#include "content/public/common/content_client.h"
 #include "content/public/common/content_switches.h"
 #include "jni/ChildProcessLauncher_jni.h"
 #include "media/base/android/media_player_android.h"
@@ -88,6 +92,16 @@ static void SetSurfacePeer(
 #endif
 }
 
+void EmptyCallback(base::ProcessHandle) {}
+
+void LaunchDownloadProcess(base::CommandLine* cmd_line, int child_process_id) {
+  scoped_ptr<base::CommandLine> cmd_line_deleter(cmd_line);
+  StartChildProcess(cmd_line->argv(), child_process_id,

[no sievers, 2016/02/02 01:37:38]

How about a different Java entry point, if all the arguments don't apply?

[qinmin, 2016/02/02 20:51:41]

Done. Call startDownloadProcess() in the java class.

+                    FileDescriptorInfoImpl::Create(),
+                    std::map<int, base::MemoryMappedFile::Region>(),
+                    base::Bind(&EmptyCallback));
+}
+
 }  // anonymous namespace
 
 // Called from ChildProcessLauncher.java when the ChildProcess was
@@ -107,6 +121,36 @@ static void OnChildProcessStarted(JNIEnv*,
   delete callback;
 }
 
+void StartDownloadProcess() {
+  base::FilePath exe_path = content::ChildProcessHost::GetChildPath(
+      content::ChildProcessHost::CHILD_NORMAL);
+  if (exe_path.empty()) {
+    NOTREACHED() << "Unable to get download process binary name.";
+    return;
+  }
+  base::CommandLine* cmd_line = new base::CommandLine(exe_path);
+  cmd_line->AppendSwitchASCII(switches::kProcessType,
+                              switches::kDownloadProcess);
+  cmd_line->AppendSwitch(switches::kNoSandbox);
+  int child_process_id = ChildProcessHostImpl::GenerateChildProcessUniqueId();
+  GetContentClient()->browser()->AppendExtraCommandLineSwitches(
+      cmd_line, child_process_id);
+
+  const base::CommandLine browser_command_line =
+      *base::CommandLine::ForCurrentProcess();
+  static const char* kForwardSwitches[] = {
+      switches::kDisableLogging,
+      switches::kEnableLogging,
+      switches::kLoggingLevel,
+  };
+  cmd_line->CopySwitchesFrom(browser_command_line, kForwardSwitches,
+                             arraysize(kForwardSwitches));
+  CHECK(!cmd_line->HasSwitch(switches::kSingleProcess));
+  BrowserThread::PostTask(
+      BrowserThread::PROCESS_LAUNCHER, FROM_HERE,
+      base::Bind(&LaunchDownloadProcess, cmd_line, child_process_id));
+}
+
 void StartChildProcess(
     const base::CommandLine::StringVector& argv,
     int child_process_id,
@@ -120,7 +164,6 @@ void StartChildProcess(
   ScopedJavaLocalRef<jobjectArray> j_argv = ToJavaArrayOfStrings(env, argv);
 
   size_t file_count = files_to_register->GetMappingSize();
-  DCHECK(file_count > 0);
 
   ScopedJavaLocalRef<jclass> j_file_info_class = base::android::GetClass(
       env, "org/chromium/content/browser/FileDescriptorInfo");