Re-fix http://crbug.com/87176, and add a test.

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index 21c20c9fa3cb30f9d94e39ee60cda8f577ca6f4b..34708a4098caa4692241db0e37cb3f410e982dc9 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -387,6 +387,7 @@ RenderProcessHostImpl::RenderProcessHostImpl(
               FROM_HERE, base::TimeDelta::FromSeconds(5),
               this, &RenderProcessHostImpl::ClearTransportDIBCache),
           is_initialized_(false),
+          child_process_launcher_factory_(base::Bind(&NewChildProcessLauncher)),
           id_(ChildProcessHostImpl::GenerateChildProcessUniqueId()),
           browser_context_(browser_context),
           storage_partition_impl_(storage_partition_impl),
@@ -539,7 +540,7 @@ bool RenderProcessHostImpl::Init() {
     // Spawn the child process asynchronously to avoid blocking the UI thread.
     // As long as there's no renderer prefix, we can use the zygote process
     // at this stage.
-    child_process_launcher_.reset(new ChildProcessLauncher(
+    child_process_launcher_ = child_process_launcher_factory_.Run(
 #if defined(OS_WIN)
         new RendererSandboxedProcessLauncherDelegate,
 #elif defined(OS_POSIX)
@@ -549,7 +550,7 @@ bool RenderProcessHostImpl::Init() {
 #endif
         cmd_line,
         GetID(),
-        this));
+        this);
 
     fast_shutdown_started_ = false;
   }
@@ -605,9 +606,11 @@ void RenderProcessHostImpl::CreateMessageFilters() {
       BrowserMainLoop::GetMediaStreamManager();
   channel_->AddFilter(new AudioInputRendererHost(audio_manager,

[Charlie Reis, 2013/06/05 19:07:10]

Does this also need to be behind the if?

[Jeffrey Yasskin, 2013/06/05 21:23:27]

The test passes with it outside the if, likely because I'm not sending any
messages that the AudioInputRendererHost wants to process using its arguments.
It looks like I could actually remove the 'if' entirely by removing the two
DCHECKs in AudioRendererHost()
(https://code.google.com/p/chromium/codesearch/#chromium/src/content/browser/r...),
which would cause it to fail only when a unittest actually sends a message that
needs to go to this filter.

I think it's slightly better to put the 'if' here, since that reduces the
dependencies of the unittest, and a unittest that's trying to test the
AudioRendererHost should probably just instantiate that and send messages
through it directly. The downside is that a test author who expects to send
messages to the RPH and have the AudioRendererHost process them will find their
bug faster if the first message they send crashes, rather than just being
ignored.

                                                  media_stream_manager));
-  channel_->AddFilter(new AudioRendererHost(
-      GetID(), audio_manager, BrowserMainLoop::GetAudioMirroringManager(),
-      media_internals, media_stream_manager));
+  if (audio_manager) {
+    channel_->AddFilter(new AudioRendererHost(
+        GetID(), audio_manager, BrowserMainLoop::GetAudioMirroringManager(),
+        media_internals, media_stream_manager));
+  }
   channel_->AddFilter(new VideoCaptureHost());
   channel_->AddFilter(new AppCacheDispatcherHost(
       storage_partition_impl_->GetAppCacheService(),
@@ -1687,7 +1690,7 @@ void RenderProcessHostImpl::OnShutdownRequest() {
   // to close, or if there are pending RenderViews being swapped back in.
   // In single process mode, we never shutdown the renderer.
   int num_active_views = GetActiveViewCount();
-  if (pending_views_ || num_active_views > 1 || run_renderer_in_process())
+  if (pending_views_ || num_active_views > 0 || run_renderer_in_process())
     return;
 
   // Notify any contents that might have swapped out renderers from this