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

This helps us get to the bottom of where the invalid blob refcount
and url calls are. It's unclear whether these are new or if they've
always occurred, as we used to ignore these messages.

R=kinuko@chromium.org, mpearson@chromium.org
BUG=602443

Review URL: https://codereview.chromium.org/1893293006

Cr-Commit-Position: refs/heads/master@{#388626}

content/browser/blob_storage/blob_dispatcher_host.cc

@@ -7,6 +7,7 @@
 #include <algorithm>
 
 #include "base/bind.h"
+#include "base/metrics/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"
@@ -24,6 +25,16 @@ using storage::BlobTransportResult;
 using storage::IPCBlobCreationCancelCode;
 
 namespace content {
+namespace {
+
+// These are used for UMA stats, don't change.
+enum RefcountOperation {
+  BDH_DECREMENT = 0,
+  BDH_INCREMENT,
+  BDH_TRACING_ENUM_LAST
+};
+
+} // namespace
 
 BlobDispatcherHost::BlobDispatcherHost(
     ChromeBlobStorageContext* blob_storage_context)
@@ -209,6 +220,8 @@ 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_ENUMERATION("Storage.Blob.InvalidReference", BDH_INCREMENT,
+                              BDH_TRACING_ENUM_LAST);
     bad_message::ReceivedBadMessage(
         this, bad_message::BDH_INVALID_REFCOUNT_OPERATION);
     return;
@@ -220,6 +233,8 @@ void BlobDispatcherHost::OnIncrementBlobRefCount(const std::string& uuid) {
 void BlobDispatcherHost::OnDecrementBlobRefCount(const std::string& uuid) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   if (uuid.empty() || !IsInUseInHost(uuid)) {
+    UMA_HISTOGRAM_ENUMERATION("Storage.Blob.InvalidReference", BDH_DECREMENT,
+                              BDH_TRACING_ENUM_LAST);
     bad_message::ReceivedBadMessage(
         this, bad_message::BDH_INVALID_REFCOUNT_OPERATION);
     return;
@@ -249,6 +264,8 @@ void BlobDispatcherHost::OnRegisterPublicBlobURL(const GURL& public_url,
   BlobStorageContext* context = this->context();
   if (uuid.empty() || !IsInUseInHost(uuid) ||
       context->registry().IsURLMapped(public_url)) {
+    UMA_HISTOGRAM_ENUMERATION("Storage.Blob.InvalidURLRegister", BDH_INCREMENT,
+                              BDH_TRACING_ENUM_LAST);
     bad_message::ReceivedBadMessage(this,
                                     bad_message::BDH_INVALID_URL_OPERATION);
     return;
@@ -260,6 +277,8 @@ void BlobDispatcherHost::OnRegisterPublicBlobURL(const GURL& public_url,
 void BlobDispatcherHost::OnRevokePublicBlobURL(const GURL& public_url) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   if (!IsUrlRegisteredInHost(public_url)) {
+    UMA_HISTOGRAM_ENUMERATION("Storage.Blob.InvalidURLRegister", BDH_DECREMENT,
+                              BDH_TRACING_ENUM_LAST);
     bad_message::ReceivedBadMessage(this,
                                     bad_message::BDH_INVALID_URL_OPERATION);
     return;

tools/metrics/histograms/histograms.xml

@@ -51639,6 +51639,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Storage.Blob.InvalidReference" enum="RefcountOperation">
+  <owner>dmurph@chromium.org</owner>
+  <summary>
+    Counts the number of times we have an invalid refcount operation. An invalid
+    increment means the blob didn't exist, and an invalid decrement means we
+    don't have any record of the blob in our host.
+  </summary>
+</histogram>
+
+<histogram name="Storage.Blob.InvalidURLRegister" enum="RefcountOperation">
+  <owner>dmurph@chromium.org</owner>
+  <summary>
+    Counts the number of times we have an invalid url registration operation. An
+    invalid increment means the blob isn't in use by the host yet or the url is
+    already mapped. An invalid decrement means the url isn't registered.
+  </summary>
+</histogram>
+
 <histogram name="Storage.Blob.ItemCount" units="Blob Items">
   <owner>dmurph@chromium.org</owner>
   <summary>
@@ -82017,6 +82035,11 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="9" label="DownloadError"/>
 </enum>
 
+<enum name="RefcountOperation" type="int">
+  <int value="0" label="Decrement"/>
+  <int value="1" label="Increment"/>
+</enum>
+
 <enum name="RemotePlaybackDeviceType" type="int">
   <int value="0" label="Cast Generic Media Player"/>
   <int value="1" label="Cast YouTube Player"/>