Implement about:tracing UI for the sampling profiler (Chromium part)

components/tracing/tracing_messages.h

 // Copyright (c) 2012 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.
 
 // Multiply-included message header, no traditional include guard.
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/sync_socket.h"
 #include "ipc/ipc_channel_handle.h"
 #include "ipc/ipc_message_macros.h"
 #include "ipc/ipc_message_utils.h"
 #include "ipc/ipc_platform_file.h"
 
 #define IPC_MESSAGE_START TracingMsgStart
 
 // Sent to all child processes to enable trace event recording.
 IPC_MESSAGE_CONTROL3(TracingMsg_BeginTracing,
                      std::string /*  category_filter_str */,
                      base::TimeTicks /* browser_time */,
                      int /* base::debug::TraceLog::Options */)
 
 // Sent to all child processes to disable trace event recording.
 IPC_MESSAGE_CONTROL0(TracingMsg_EndTracing)
 
+// Sent to all child processes to start continuous sampling tracing.
+IPC_MESSAGE_CONTROL1(TracingMsg_BeginContinuousSamplingTracing,
+                     base::TimeTicks /* browser_time */)
+
+// Sent to all child processes to stop continuous sampling tracing.
+IPC_MESSAGE_CONTROL0(TracingMsg_EndContinuousSamplingTracing)
+
+// Sent to all child processes to dump a result of continuous sampling tracing.
+IPC_MESSAGE_CONTROL0(TracingMsg_ShowContinuousSamplingTracing)
+
 // Sent to all child processes to get trace buffer fullness.
 IPC_MESSAGE_CONTROL0(TracingMsg_GetTraceBufferPercentFull)
 
 // Sent to all child processes to set watch event.
 IPC_MESSAGE_CONTROL2(TracingMsg_SetWatchEvent,
                      std::string /* category_name */,
                      std::string /* event_name */)
 
 // Sent to all child processes to clear watch event.
 IPC_MESSAGE_CONTROL0(TracingMsg_CancelWatchEvent)
 
 // Notify the browser that this child process supports tracing.
 IPC_MESSAGE_CONTROL0(TracingHostMsg_ChildSupportsTracing)
 
-// Reply from child processes acking ChildProcessMsg_TraceChangeStatus(false).
+// Reply from child processes acking TracingMsg_EndTracing.
 IPC_MESSAGE_CONTROL1(TracingHostMsg_EndTracingAck,
                      std::vector<std::string> /* known_categories */)
 
+// Reply from child processes acking TracingMsg_ShowContinuousSamplingTracing.
+IPC_MESSAGE_CONTROL0(TracingHostMsg_ShowContinuousSamplingTracingAck)
+
 // Sent if the trace buffer becomes full.
 IPC_MESSAGE_CONTROL1(TracingHostMsg_TraceNotification,
                      int /* base::debug::TraceLog::Notification */)
 
 // Child processes send trace data back in JSON chunks.
 IPC_MESSAGE_CONTROL1(TracingHostMsg_TraceDataCollected,
                      std::string /*json trace data*/)
 
+// Child processes send trace data of continuous sampling tracing back
+// in JSON chunks.
+IPC_MESSAGE_CONTROL1(TracingHostMsg_ContinuousSamplingTraceDataCollected,
+                     std::string /*json trace data*/)
+
 // Reply to TracingMsg_GetTraceBufferPercentFull.
 IPC_MESSAGE_CONTROL1(TracingHostMsg_TraceBufferPercentFullReply,
                      float /*trace buffer percent full*/)