Replace push_back with emplace_back

Change-Id: Ie3d2ebaf98ca26de363dd961f64d5461b909ec14
Reviewed-on: https://chromium-review.googlesource.com/1089803Reviewed-by: Mike Wittman <wittman@chromium.org>
Commit-Queue: Xi Cheng <chengx@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565097}

base/profiler/native_stack_sampler_win.cc

@@ -519,9 +519,9 @@ void NativeStackSamplerWin::CopyToSample(
   sample->frames.reserve(stack.size());
 
   for (const auto& frame : stack) {
-    sample->frames.push_back(StackSamplingProfiler::Frame(
+    sample->frames.emplace_back(
         reinterpret_cast<uintptr_t>(frame.instruction_pointer),
-        GetModuleIndex(frame.module.Get(), modules)));
+        GetModuleIndex(frame.module.Get(), modules));
   }
 }