Make stack sampling profiler sample beyond startup.

chrome/common/stack_sampling_configuration.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_COMMON_STACK_SAMPLING_CONFIGURATION_H_
 #define CHROME_COMMON_STACK_SAMPLING_CONFIGURATION_H_
 
 #include <string>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/profiler/stack_sampling_profiler.h"
+#include "components/metrics/call_stack_profile_metrics_provider.h"
 
 namespace base {
 class CommandLine;
 }  // namespace base
 
 // StackSamplingConfiguration chooses a configuration for the enable state of
 // the stack sampling profiler across all processes. This configuration is
 // determined once at browser process startup. Configurations for child
 // processes are communicated via command line arguments.
 class StackSamplingConfiguration {
  public:
   StackSamplingConfiguration();
 
   // Get the stack sampling params to use for this process.
   base::StackSamplingProfiler::SamplingParams
-      GetSamplingParamsForCurrentProcess() const;
+  GetSamplingParamsForCurrentProcess() const;
+
+  // Returns the profiler callback to use for this process.
+  base::StackSamplingProfiler::CompletedCallback
+  GetProfilerCallbackForCurrentProcess();
 
   // Returns true if the profiler should be started for the current process.
   bool IsProfilerEnabledForCurrentProcess() const;
 
   // Get the synthetic field trial configuration. Returns true if a synthetic
   // field trial should be registered. This should only be called from the
   // browser process. When run at startup, the profiler must use a synthetic
   // field trial since it runs before the metrics field trials are initialized.
   bool GetSyntheticFieldTrial(std::string* trial_name,
                               std::string* group_name) const;
@@ skipping 35 matching lines @@
       const std::vector<Variation>& variations);
 
   // Generates sampling profiler configurations for all processes.
   static ProfileConfiguration GenerateConfiguration();
 
   // In the browser process this represents the configuration to use across all
   // Chrome processes. In the child processes it is always
   // PROFILE_FROM_COMMAND_LINE.
   const ProfileConfiguration configuration_;
 
+  // The current profiling params. Not const since these may be changed when
+  // transitioning from start-up profiling to periodic profiling.
+  metrics::CallStackProfileParams profile_params_;
+
   DISALLOW_COPY_AND_ASSIGN(StackSamplingConfiguration);
 };
 
 #endif  // CHROME_COMMON_STACK_SAMPLING_CONFIGURATION_H_