gpu: Maintain the deferred log messages separately from the IPC messages.

content/gpu/gpu_main.cc

Index: content/gpu/gpu_main.cc
diff --git a/content/gpu/gpu_main.cc b/content/gpu/gpu_main.cc
index 2d6ea76190b1a0e4bb21bfbfecb63ab88d19b193..2518e539bc8a55102c91f54d86345cf8403be521 100644
--- a/content/gpu/gpu_main.cc
+++ b/content/gpu/gpu_main.cc
@@ -106,10 +106,11 @@ bool GpuProcessLogMessageHandler(int severity,
                                  const char* file, int line,
                                  size_t message_start,
                                  const std::string& str) {
-  std::string header = str.substr(0, message_start);
-  std::string message = str.substr(message_start);
-  deferred_messages.Get().push(
-      new GpuHostMsg_OnLogMessage(severity, header, message));
+  GpuChildThread::LogMessage log;
+  log.severity = severity;
+  log.header = str.substr(0, message_start);
+  log.message = str.substr(message_start);
+  deferred_messages.Get().push(std::move(log));
   return false;
 }