[Blob] Added error reporting metrics to invalid message errors.

content/browser/blob_storage/blob_dispatcher_host.cc

 // Copyright 2016 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.
 
 #include "content/browser/blob_storage/blob_dispatcher_host.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
+#include "base/metrics/histogram.h"

[Mark P, 2016/04/19 19:34:52]

Prefer histogram_macros.h

 #include "content/browser/bad_message.h"
 #include "content/browser/fileapi/chrome_blob_storage_context.h"
 #include "content/common/fileapi/webblob_messages.h"
 #include "ipc/ipc_platform_file.h"
 #include "storage/browser/blob/blob_storage_context.h"
 #include "storage/browser/blob/blob_transport_result.h"
 #include "storage/common/blob_storage/blob_item_bytes_request.h"
 #include "storage/common/blob_storage/blob_item_bytes_response.h"
 #include "storage/common/data_element.h"
 #include "url/gurl.h"
@@ skipping 182 matching lines @@
   }
   VLOG(1) << "Blob construction of " << uuid << " cancelled by renderer. "
           << " Reason: " << static_cast<int>(code) << ".";
   async_builder_.CancelBuildingBlob(uuid, code, context);
 }
 
 void BlobDispatcherHost::OnIncrementBlobRefCount(const std::string& uuid) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   BlobStorageContext* context = this->context();
   if (uuid.empty() || !context->registry().HasEntry(uuid)) {
+    UMA_HISTOGRAM_BOOLEAN("Storage.Blob.InvalidReferenceInc", true);

[Mark P, 2016/04/19 19:34:52]

If you're only emitting true to this histogram, why don't you simply do
Storage.Blob.InvalidReference and have true = Increment and false = Decrement?

     bad_message::ReceivedBadMessage(
         this, bad_message::BDH_INVALID_REFCOUNT_OPERATION);
     return;
   }
   context->IncrementBlobRefCount(uuid);
   blobs_inuse_map_[uuid] += 1;
 }
 
 void BlobDispatcherHost::OnDecrementBlobRefCount(const std::string& uuid) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   if (uuid.empty() || !IsInUseInHost(uuid)) {
+    UMA_HISTOGRAM_BOOLEAN("Storage.Blob.InvalidReferenceDec", true);
     bad_message::ReceivedBadMessage(
         this, bad_message::BDH_INVALID_REFCOUNT_OPERATION);
     return;
   }
   BlobStorageContext* context = this->context();
   context->DecrementBlobRefCount(uuid);
   blobs_inuse_map_[uuid] -= 1;
   if (blobs_inuse_map_[uuid] == 0) {
     blobs_inuse_map_.erase(uuid);
     // If the blob has been deleted in the context and we're still building it,
     // this means we have no references waiting to read it. Clear the building
     // state and send a cancel message to the renderer.
     if (async_builder_.IsBeingBuilt(uuid) &&
         !context->registry().HasEntry(uuid)) {
       async_builder_.CancelBuildingBlob(
           uuid, IPCBlobCreationCancelCode::BLOB_DEREFERENCED_WHILE_BUILDING,
           context);
       Send(new BlobStorageMsg_CancelBuildingBlob(
           uuid, IPCBlobCreationCancelCode::BLOB_DEREFERENCED_WHILE_BUILDING));
     }
   }
 }
 
 void BlobDispatcherHost::OnRegisterPublicBlobURL(const GURL& public_url,
                                                  const std::string& uuid) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   BlobStorageContext* context = this->context();
   if (uuid.empty() || !IsInUseInHost(uuid) ||
       context->registry().IsURLMapped(public_url)) {
+    UMA_HISTOGRAM_BOOLEAN("Storage.Blob.InvalidURLRegister", true);

[Mark P, 2016/04/19 19:34:52]

analogous comment here

     bad_message::ReceivedBadMessage(this,
                                     bad_message::BDH_INVALID_URL_OPERATION);
     return;
   }
   context->RegisterPublicBlobURL(public_url, uuid);
   public_blob_urls_.insert(public_url);
 }
 
 void BlobDispatcherHost::OnRevokePublicBlobURL(const GURL& public_url) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   if (!IsUrlRegisteredInHost(public_url)) {
+    UMA_HISTOGRAM_BOOLEAN("Storage.Blob.InvalidURLRevoke", true);
     bad_message::ReceivedBadMessage(this,
                                     bad_message::BDH_INVALID_URL_OPERATION);
     return;
   }
   context()->RevokePublicBlobURL(public_url);
   public_blob_urls_.erase(public_url);
 }
 
 storage::BlobStorageContext* BlobDispatcherHost::context() {
   return blob_storage_context_->context();
@@ skipping 58 matching lines @@
     context->RevokePublicBlobURL(url);
   }
   for (const auto& uuid_refnum_pair : blobs_inuse_map_) {
     for (int i = 0; i < uuid_refnum_pair.second; ++i)
       context->DecrementBlobRefCount(uuid_refnum_pair.first);
   }
   async_builder_.CancelAll(context);
 }
 
 }  // namespace content