Use a common buffer across all instances for stack-copy.

base/profiler/native_stack_sampler.cc

Index: base/profiler/native_stack_sampler.cc
diff --git a/base/profiler/native_stack_sampler.cc b/base/profiler/native_stack_sampler.cc
index 968455f13e007c7b2c26290249a79883c8805d2d..e513761ae0a160e097db3cb611c8fe37e8139a0f 100644
--- a/base/profiler/native_stack_sampler.cc
+++ b/base/profiler/native_stack_sampler.cc
@@ -6,6 +6,12 @@
 
 namespace base {
 
+NativeStackSampler::StackBuffer::StackBuffer(size_t buffer_size)
+    : buffer_(new int[(buffer_size + sizeof(int) - 1) / sizeof(int)]),
+      size_(buffer_size) {}
+
+NativeStackSampler::StackBuffer::~StackBuffer() {}
+
 NativeStackSampler::NativeStackSampler() {}
 
 NativeStackSampler::~NativeStackSampler() {}