Improve multi-process debugging.

mojo/shell/child_process_host.cc

 // Copyright 2014 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 "mojo/shell/child_process_host.h"
 
 #include "base/base_switches.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/process/kill.h"
 #include "base/process/launch.h"
+#include "base/stl_util.h"
+#include "base/strings/string_split.h"
 #include "base/task_runner.h"
 #include "base/task_runner_util.h"
 #include "mojo/edk/embedder/embedder.h"
 #include "mojo/public/cpp/system/core.h"
 #include "mojo/shell/context.h"
 #include "mojo/shell/switches.h"
 #include "mojo/shell/task_runners.h"
 
 namespace mojo {
 namespace shell {
 
-ChildProcessHost::ChildProcessHost(Context* context)
-    : context_(context), channel_info_(nullptr) {
+ChildProcessHost::ChildProcessHost(Context* context, const std::string& name)
+    : context_(context), name_(name), channel_info_(nullptr) {
   platform_channel_ = platform_channel_pair_.PassServerHandle();
   CHECK(platform_channel_.is_valid());
 }
 
 ChildProcessHost::~ChildProcessHost() {
   if (child_process_.IsValid()) {
     LOG(WARNING) << "Destroying ChildProcessHost with unjoined child";
     child_process_.Close();
   }
 }
@@ skipping 56 matching lines @@
 bool ChildProcessHost::DoLaunch() {
   static const char* kForwardSwitches[] = {
       switches::kTraceToConsole, switches::kV, switches::kVModule,
   };
 
   const base::CommandLine* parent_command_line =
       base::CommandLine::ForCurrentProcess();
   base::CommandLine child_command_line(parent_command_line->GetProgram());
   child_command_line.CopySwitchesFrom(*parent_command_line, kForwardSwitches,
                                       arraysize(kForwardSwitches));
+  child_command_line.AppendSwitchASCII(switches::kApp, name_);

[sky, 2015/04/23 21:48:54]

Should you only do this if name_ is not empty?

[jam, 2015/04/23 22:18:44]

I don't expect name_ to be empty. i added a dcheck

   child_command_line.AppendSwitch(switches::kChildProcess);
+  if (parent_command_line->HasSwitch(switches::kWaitForDebugger)) {
+    std::vector<std::string> apps_to_debug;
+    base::SplitString(
+        parent_command_line->GetSwitchValueASCII(switches::kWaitForDebugger),
+        ',', &apps_to_debug);
+    if (apps_to_debug.empty() || ContainsValue(apps_to_debug, name_))
+      child_command_line.AppendSwitch(switches::kWaitForDebugger);
+  }
 
   embedder::HandlePassingInformation handle_passing_info;
   platform_channel_pair_.PrepareToPassClientHandleToChildProcess(
       &child_command_line, &handle_passing_info);
 
   base::LaunchOptions options;
 #if defined(OS_WIN)
   options.start_hidden = true;
   options.handles_to_inherit = &handle_passing_info;
 #elif defined(OS_POSIX)
@@ skipping 19 matching lines @@
 
 void ChildProcessHost::DidCreateChannel(embedder::ChannelInfo* channel_info) {
   DVLOG(2) << "AppChildProcessHost::DidCreateChannel()";
 
   CHECK(channel_info);
   channel_info_ = channel_info;
 }
 
 }  // namespace shell
 }  // namespace mojo