Remove unused IPC::Message priority.

ipc/ipc_message.h

Index: ipc/ipc_message.h
diff --git a/ipc/ipc_message.h b/ipc/ipc_message.h
index 42090166b38a9d9af94db565fc419bc0fb3e9949..c0ee283e211cf6892635e84f4669f18301187ccd 100644
--- a/ipc/ipc_message.h
+++ b/ipc/ipc_message.h
@@ -34,17 +34,10 @@ struct LogData;
 
 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     = 0x03,  // Low 2 bits of store the priority value.
     SYNC_BIT          = 0x04,

[jam, 2013/10/25 00:26:24]

while it's a positive that we get rid of unused priority bits, it's a bit odd
reading this and seeing unused bits.

hmm, perhaps just have

UNUSED = 0x03;
?

     REPLY_BIT         = 0x08,
     REPLY_ERROR_BIT   = 0x10,
@@ -57,22 +50,17 @@ class IPC_EXPORT Message : public Pickle {
 
   Message();
 
-  // Initialize a message with a user-defined type, priority value, and
-  // destination WebView ID.
-  Message(int32 routing_id, uint32 type, PriorityValue priority);
+  // Initialize a message with routing ID and a user-defined type.
+  Message(int32 routing_id, uint32 type);
 
   // Initializes a message from a const block of data.  The data is not copied;
   // instead the data is merely referenced by this message.  Only const methods
   // should be used on the message when initialized this way.
-  Message(const char* data, int data_len);
+  Message(const char* data, size_t data_len);
 
   Message(const Message& other);
   Message& operator=(const Message& other);
 
-  PriorityValue priority() const {
-    return static_cast<PriorityValue>(header()->flags & PRIORITY_MASK);
-  }
-
   // True if this is a synchronous message.
   void set_sync() {
     header()->flags |= SYNC_BIT;