Update instrumentation for many different bugs based on new UMA data.

content/browser/webui/url_data_manager_backend.cc

Index: content/browser/webui/url_data_manager_backend.cc
diff --git a/content/browser/webui/url_data_manager_backend.cc b/content/browser/webui/url_data_manager_backend.cc
index 92f7bc6b2ee7268a8eeeb2bb92289c2045fd1bdc..d79a617832fed80158281fdd2a9a3f9e880c27c6 100644
--- a/content/browser/webui/url_data_manager_backend.cc
+++ b/content/browser/webui/url_data_manager_backend.cc
@@ -337,11 +337,6 @@ void URLRequestChromeJob::DataAvailable(base::RefCountedMemory* bytes) {
     int bytes_read;
     if (pending_buf_.get()) {
       CHECK(pending_buf_->data());
-      // TODO(pkasting): Remove ScopedTracker below once crbug.com/455423 is
-      // fixed.
-      tracked_objects::ScopedTracker tracking_profile(
-          FROM_HERE_WITH_EXPLICIT_FUNCTION(
-              "455423 URLRequestChromeJob::CompleteRead"));
       CompleteRead(pending_buf_.get(), pending_buf_size_, &bytes_read);
       pending_buf_ = NULL;
       NotifyReadComplete(bytes_read);