Check for a restarted GPU process in OnCreateViewCommandBuffer.

content/browser/renderer_host/gpu_message_filter.cc

Index: content/browser/renderer_host/gpu_message_filter.cc
diff --git a/content/browser/renderer_host/gpu_message_filter.cc b/content/browser/renderer_host/gpu_message_filter.cc
index 856d14b9ecc83e356a5f25098b7ec166d97e7ddd..9a3bf2558b10edf5515557ce3c8848b1f51c158a 100644
--- a/content/browser/renderer_host/gpu_message_filter.cc
+++ b/content/browser/renderer_host/gpu_message_filter.cc
@@ -103,6 +103,25 @@ void GpuMessageFilter::EndFrameSubscription(int route_id) {
   }
 }
 
+GpuProcessHost* GpuMessageFilter::GetGpuProcessHost(
+    CauseForGpuLaunch cause_for_gpu_launch) {
+  GpuProcessHost* host = GpuProcessHost::FromID(gpu_process_id_);
+  if (!host) {
+    host = GpuProcessHost::Get(GpuProcessHost::GPU_PROCESS_KIND_SANDBOXED,
+                               cause_for_gpu_launch);
+    if (!host) {
+      return NULL;
+    }
+
+    gpu_process_id_ = host->host_id();
+
+    // Apply all frame subscriptions to the new GpuProcessHost.
+    BeginAllFrameSubscriptions();
+  }
+
+  return host;
+}
+
 void GpuMessageFilter::OnEstablishGpuChannel(
     CauseForGpuLaunch cause_for_gpu_launch,
     IPC::Message* reply_ptr) {
@@ -116,20 +135,11 @@ void GpuMessageFilter::OnEstablishGpuChannel(
   // terminates, the renderer process will not find itself unknowingly sending
   // IPCs to a newly launched GPU process. Also, I will rename this function
   // to something like OnCreateGpuProcess.
-  GpuProcessHost* host = GpuProcessHost::FromID(gpu_process_id_);
+  GpuProcessHost* host = GetGpuProcessHost(cause_for_gpu_launch);
   if (!host) {
-    host = GpuProcessHost::Get(GpuProcessHost::GPU_PROCESS_KIND_SANDBOXED,
-                               cause_for_gpu_launch);
-    if (!host) {
-      reply->set_reply_error();
-      Send(reply.release());
-      return;
-    }
-
-    gpu_process_id_ = host->host_id();
-
-    // Apply all frame subscriptions to the new GpuProcessHost.
-    BeginAllFrameSubscriptions();
+    reply->set_reply_error();
+    Send(reply.release());
+    return;
   }
 
   bool share_contexts = true;
@@ -169,7 +179,9 @@ void GpuMessageFilter::OnCreateViewCommandBuffer(
     compositing_surface = gfx::GLSurfaceHandle();
   }
 
-  GpuProcessHost* host = GpuProcessHost::FromID(gpu_process_id_);
+  GpuProcessHost* host = GetGpuProcessHost(
+      // This is currently the only creator of a view command buffer.
+      CAUSE_FOR_GPU_LAUNCH_WEBGRAPHICSCONTEXT3DCOMMANDBUFFERIMPL_INITIALIZE);

[piman, 2014/05/08 03:29:21]

So, relaunching the GPU process is not actually good, because while it will give
you a context, it will be on a different channel than the GpuChannelHost you
asked it from.
So on the renderer side, you will have a discrepancy, and trying to send
messages to this command buffer will go on the wrong/old channel and fail.

I think we had a discussion about this with Dana, and the conclusion was IIRC
that we should handle this on the renderer side, if the CreateViewCommandBuffer
fails, that should trigger failure of the GpuChannelHost.

I think that's https://code.google.com/p/chromium/issues/detail?id=356876

[Ken Russell (switch to Gerrit), 2014/05/09 01:36:13]

Thanks for the feedback. I'll redo this as a check in the renderer process and
lose the GpuChannelHost from the RenderThreadImpl if this happens.

Currently tracking down remaining race conditions even if this bug were fixed.
Will post either an updated CL or a new one once everything is working reliably.

   if (!host || compositing_surface.is_null()) {
     // TODO(apatrick): Eventually, this IPC message will be routed to a
     // GpuProcessStub with a particular routing ID. The error will be set if