Stack sampling profiler: run the profiler in the GPU process on trunk builds

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"
 
-// Chooses a configuration for the stack sampling profiler for browser process
-// startup. This must live outside of ChromeBrowserMainParts so it can be
-// friended by ChromeMetricsServiceAccessor.
+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:
   // This callback indirection is required to avoid a DEPS on
   // chrome/browser/metrics.
   using RegisterSyntheticFieldTrialFunction = base::Callback<bool(
       const std::string& trial_name,
       const std::string& group_name)>;
+
   StackSamplingConfiguration();
 
-  // Get the stack sampling params to use for this session.
-  base::StackSamplingProfiler::SamplingParams GetSamplingParams() const;
+  // Get the stack sampling params to use for this process.
+  base::StackSamplingProfiler::SamplingParams
+      GetSamplingParamsForCurrentProcess() const;
 
-  // Returns true if the profiler should be started at all.
-  bool IsProfilerEnabled() const;
+  // Returns true if the profiler should be started for the current process.
+  bool IsProfilerEnabledForCurrentProcess() const;
 
-  // Register the chosen configuration as a synthetic field trial.
+  // Register the chosen configuration as a synthetic field trial. This should
+  // only be called from the browser process.
   void RegisterSyntheticFieldTrial(
       const RegisterSyntheticFieldTrialFunction& register_field_trial) const;
 
+  // Add a command line switch that instructs the child process to run the
+  // profiler. This should only be called from the browser process.
+  void AppendCommandLineSwitchForChildProcess(
+      const std::string process_type,

[Ilya Sherman, 2016/09/28 01:02:15]

nit: Did you mean to pass by const-reference?   We generally don't pass by const
copy.

[Mike Wittman, 2016/09/28 19:34:26]

Oops, yes that was the intent. Done.

+      base::CommandLine* command_line) const;
+
+  // Returns the StackSamplingConfiguration for the process.
+  static StackSamplingConfiguration* Get();
+
  private:
   enum ProfileConfiguration {
+    // Chrome-wide configurations set in the browser process.
     PROFILE_DISABLED,
     PROFILE_CONTROL,
-    PROFILE_NO_SAMPLES,  // Run the profiler thread, but don't collect profiles.
-    PROFILE_5HZ,
-    PROFILE_10HZ,
-    PROFILE_100HZ
+    PROFILE_BROWSER_PROCESS,
+    PROFILE_GPU_PROCESS,
+    PROFILE_BROWSER_AND_GPU_PROCESS,
+
+    // Configuration set in the child processes, which receive their enable
+    // state on the command line from the browser process.
+    PROFILE_FROM_COMMAND_LINE
   };
 
+  // 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 alwasys
+  // PROFILE_FROM_COMMAND_LINE.
   const ProfileConfiguration configuration_;
 
   DISALLOW_COPY_AND_ASSIGN(StackSamplingConfiguration);
 };
 
 #endif  // CHROME_COMMON_STACK_SAMPLING_CONFIGURATION_H_