Revert "Temporarily add UMA histogram for IPC message sizes."

This reverts commit 5961c6d.

Reason for revert: enough data was collected (see the bug).

BUG=529940

Review URL: https://codereview.chromium.org/1417583006

Cr-Commit-Position: refs/heads/master@{#356935}

ipc/ipc_channel_reader.cc

@@ -6,7 +6,6 @@
 
 #include <algorithm>
 
-#include "base/metrics/histogram_macros.h"
 #include "ipc/ipc_listener.h"
 #include "ipc/ipc_logging.h"
 #include "ipc/ipc_message.h"
@@ -137,9 +136,6 @@ bool ChannelReader::TranslateInputData(const char* input_data,
 bool ChannelReader::HandleTranslatedMessage(
     Message* translated_message,
     const AttachmentIdVector& attachment_ids) {
-  UMA_HISTOGRAM_MEMORY_KB(
-      "Memory.IPCChannelReader.ReceivedMessageSize",
-      static_cast<base::HistogramBase::Sample>(translated_message->size()));
 
   // Immediately handle internal messages.
   if (IsInternalMessage(*translated_message)) {

tools/metrics/histograms/histograms.xml

@@ -18928,6 +18928,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="Memory.IPCChannelReader.ReceivedMessageSize" units="bytes">
+  <obsolete>
+    Obsolete as of 11/2015
+  </obsolete>
   <owner>dskiba@chromium.org</owner>
   <summary>Size of messages received by IPC::ChannelReader.</summary>
 </histogram>