Avoid holding locks across sync IPCs in command buffer

gpu/command_buffer/client/share_group.cc

Index: gpu/command_buffer/client/share_group.cc
diff --git a/gpu/command_buffer/client/share_group.cc b/gpu/command_buffer/client/share_group.cc
index 96ab8d181be01ab52edda453043ad4bbd451bf78..46413d17a8c07e0faf1b159049d14d156d284e88 100644
--- a/gpu/command_buffer/client/share_group.cc
+++ b/gpu/command_buffer/client/share_group.cc
@@ -49,18 +49,21 @@ class IdHandler : public IdHandlerInterface {
   virtual bool FreeIds(
       GLES2Implementation* gl_impl,
       GLsizei n, const GLuint* ids, DeleteFn delete_fn) OVERRIDE {
-    base::AutoLock auto_lock(lock_);
-
-    for (GLsizei ii = 0; ii < n; ++ii) {
-      id_allocator_.FreeID(ids[ii]);
-    }
-
+    // Possibly may do a synchronous ipc, so can't hold a lock across it on
+    // pepper: http://crbug.com/418651
     (gl_impl->*delete_fn)(n, ids);
     // We need to ensure that the delete call is evaluated on the service side
     // before any other contexts issue commands using these client ids.
     // TODO(vmiura): Can remove this by virtualizing internal ids, however
     // this code only affects PPAPI for now.
     gl_impl->helper()->CommandBufferHelper::Flush();
+
+    base::AutoLock auto_lock(lock_);
+
+    for (GLsizei ii = 0; ii < n; ++ii) {
+      id_allocator_.FreeID(ids[ii]);
+    }
+
     return true;
   }