Add async trace events to trace progress of IPC messages

ipc/ipc_message.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.
 
 #ifndef IPC_IPC_MESSAGE_H_
 #define IPC_IPC_MESSAGE_H_
 
 #include <string>
 
 #include "base/basictypes.h"
+#include "base/debug/trace_event.h"
 #include "base/pickle.h"
 #include "ipc/ipc_export.h"
 
 // TODO(brettw) remove this and update files that depend on this being included
 // from here.
 #include "ipc/ipc_sender.h"
 
 // Ipc logging adds a dependency from the 'chrome' target on all ipc message
 // classes. In a component build, this would require exporting all message
 // classes, so don't support ipc logging in the components build.
@@ skipping 21 matching lines @@
 
 class IPC_EXPORT Message : public Pickle {
  public:
   enum PriorityValue {
     PRIORITY_LOW = 1,
     PRIORITY_NORMAL,
     PRIORITY_HIGH
   };
 
   // Bit values used in the flags field.
+  // Upper 24 bits of flags store a reference number, so this enum is limited to
+  // 8 bits.
   enum {
-    PRIORITY_MASK     = 0x0003,  // Low 2 bits of store the priority value.
-    SYNC_BIT          = 0x0004,
-    REPLY_BIT         = 0x0008,
-    REPLY_ERROR_BIT   = 0x0010,
-    UNBLOCK_BIT       = 0x0020,
-    PUMPING_MSGS_BIT  = 0x0040,
-    HAS_SENT_TIME_BIT = 0x0080,
+    PRIORITY_MASK     = 0x03,  // Low 2 bits of store the priority value.
+    SYNC_BIT          = 0x04,
+    REPLY_BIT         = 0x08,
+    REPLY_ERROR_BIT   = 0x10,
+    UNBLOCK_BIT       = 0x20,
+    PUMPING_MSGS_BIT  = 0x40,
+    HAS_SENT_TIME_BIT = 0x80,
   };
 
   virtual ~Message();
 
   Message();
 
   // Initialize a message with a user-defined type, priority value, and
   // destination WebView ID.
   Message(int32 routing_id, uint32 type, PriorityValue priority);
 
@@ skipping 144 matching lines @@
   // The following four functions are needed so we can log sync messages with
   // delayed replies.  We stick the log data from the sent message into the
   // reply message, so that when it's sent and we have the output parameters
   // we can log it.  As such, we set a flag on the sent message to not log it.
   void set_sync_log_data(LogData* data) const { log_data_ = data; }
   LogData* sync_log_data() const { return log_data_; }
   void set_dont_log() const { dont_log_ = true; }
   bool dont_log() const { return dont_log_; }
 #endif
 
+  // Called at various points between send and receive to track message.
+  void TraceMessageStep() {
+    TRACE_EVENT_ASYNC_BEGIN_STEP0("ipc", "IPC", header()->flags, NULL);
+  }
+
  protected:
   friend class Channel;
   friend class MessageReplyDeserializer;
   friend class SyncMessage;
 
 #pragma pack(push, 4)
   struct Header : Pickle::Header {
     int32 routing;  // ID of the view that this message is destined for
     uint32 type;    // specifies the user-defined message type
     uint32 flags;   // specifies control flags for the message
@@ skipping 47 matching lines @@
   MSG_ROUTING_NONE = -2,
 
   // indicates a general message not sent to a particular tab.
   MSG_ROUTING_CONTROL = kint32max,
 };
 
 #define IPC_REPLY_ID 0xFFFFFFF0  // Special message id for replies
 #define IPC_LOGGING_ID 0xFFFFFFF1  // Special message id for logging
 
 #endif  // IPC_IPC_MESSAGE_H_