Add histogram for image errors.

content/browser/loader/resource_dispatcher_host_impl.cc

 // 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.
 
 // See http://dev.chromium.org/developers/design-documents/multi-process-resource-loading
 
 #include "content/browser/loader/resource_dispatcher_host_impl.h"
 
 #include <set>
 #include <vector>
@@ skipping 738 matching lines @@
 
     if (loader->request()->url().SchemeIsSecure() &&
         loader->request()->url().host() == "www.google.com") {
       UMA_HISTOGRAM_CUSTOM_ENUMERATION(
           "Net.ErrorCodesForHTTPSGoogleMainFrame2",
           -loader->request()->status().error(),
           base::CustomHistogram::ArrayToCustomRanges(
               kAllNetErrorCodes, arraysize(kAllNetErrorCodes)));
     }
   } else {
+    if (info->GetResourceType() == ResourceType::IMAGE) {
+      UMA_HISTOGRAM_CUSTOM_ENUMERATION(
+          "Net.ErrorCodesForImages",
+          -loader->request()->status().error(),
+          base::CustomHistogram::ArrayToCustomRanges(
+              kAllNetErrorCodes, arraysize(kAllNetErrorCodes)));

[Ilya Sherman, 2013/04/26 23:59:10]

Can you use a sparse histogram here?  (The corresponding macro is
UMA_HISTOGRAM_SPARSE_SLOWLY.)

[jar (doing other things), 2013/04/27 00:48:58]

+1

On 2013/04/26 23:59:10, Ilya Sherman wrote:

[James Simonsen, 2013/04/27 00:57:07]

If we're going to do that, we should update all of them in this file. I thought
this one was okay because it matched the rest of the file.

[jar (doing other things), 2013/04/27 01:00:53]

SGTM

The list has gotten long (so memory utilization is high), and this histogram
*should* be rarely augmented (and when it is, it is dwarfed by the compute cost
that got us here typically), so this "map and lock" based histogram is now a
better choice.  The good news is that existing histograms (with 1-wide buckets)
should be completely compatible, so there is no need to change the names, or the
histograms.xml file.


On 2013/04/27 00:57:07, James Simonsen wrote:

[Stephen, 2013/04/27 03:02:41]

OK so IIUC the code here should be
UMA_HISTOGRAM_SPARSE_SLOWLY("Net.ErrorCodesForImages",
-loader->request()->status().error()); and the other CUSTOM_ENUMERATION macros
should be updated similarly.  Is that right?

On 2013/04/27 01:00:53, jar wrote:

[Ilya Sherman, 2013/04/27 23:06:23]

Assuming that the expression "-loader->request()->status().error()" gives the
net error code, then yes :)
 
Yeah, sparse histograms are relatively new, so there's a lot of existing
histograms like these that would be good to move over.

+    }
     // This enumeration has "2" appended to distinguish it from older versions.
     UMA_HISTOGRAM_CUSTOM_ENUMERATION(
         "Net.ErrorCodesForSubresources2",
         -loader->request()->status().error(),
         base::CustomHistogram::ArrayToCustomRanges(
             kAllNetErrorCodes, arraysize(kAllNetErrorCodes)));
   }
 
   // Destroy the ResourceLoader.
   RemovePendingRequest(info->GetChildID(), info->GetRequestID());
@@ skipping 1022 matching lines @@
   DelegateMap::iterator it = delegate_map_.find(id);
   DCHECK(it->second->HasObserver(delegate));
   it->second->RemoveObserver(delegate);
   if (it->second->size() == 0) {
     delete it->second;
     delegate_map_.erase(it);
   }
 }
 
 }  // namespace content