[memory-infra] Log reasons for memory dump failure

components/tracing/child/child_memory_dump_manager_delegate_impl.cc

Index: components/tracing/child/child_memory_dump_manager_delegate_impl.cc
diff --git a/components/tracing/child/child_memory_dump_manager_delegate_impl.cc b/components/tracing/child/child_memory_dump_manager_delegate_impl.cc
index c2824f1bd8f6271a3ddf282a5e3735af8d92e58f..9eac6c9967b5054a91a1655c07d52185f1ec6aff 100644
--- a/components/tracing/child/child_memory_dump_manager_delegate_impl.cc
+++ b/components/tracing/child/child_memory_dump_manager_delegate_impl.cc
@@ -75,8 +75,11 @@ void ChildMemoryDumpManagerDelegateImpl::RequestGlobalMemoryDump(
 
   // Bail out if we receive a dump request from the manager before the
   // ChildTraceMessageFilter has been initialized.
-  if (!ctmf_task_runner)
+  if (!ctmf_task_runner) {
+    VLOG(1) << "Process memory dump failed because child trace message filter "

[Primiano Tucci (use gerrit), 2016/06/08 18:00:45]

and use the same kConstant here

[petrcermak, 2016/06/09 09:46:09]

Done.

+            << "hasn't been initialized";
     return AbortDumpRequest(args, callback);
+  }
 
   // Make sure we access |ctmf_| only on the thread where it lives to avoid
   // races on shutdown.
@@ -92,8 +95,11 @@ void ChildMemoryDumpManagerDelegateImpl::RequestGlobalMemoryDump(
 
   // The ChildTraceMessageFilter could have been destroyed while hopping on the
   // right thread. If this is the case, bail out.
-  if (!ctmf_)
+  if (!ctmf_) {
+    VLOG(1) << "Process memory dump failed because child trace message filter "
+            << "has been destroyed";

[ssid, 2016/06/08 18:12:41]

destroyed while collecting the dump or something?

[petrcermak, 2016/06/09 09:46:09]

Added "while switching threads"

     return AbortDumpRequest(args, callback);
+  }
 
   // Send the request up to the browser process' MessageDumpmanager.
   ctmf_->SendGlobalMemoryDumpRequest(args, callback);