Added tracing to data-manager's loading of resources.

chrome/browser/ui/webui/chrome_url_data_manager_backend.cc

Index: chrome/browser/ui/webui/chrome_url_data_manager_backend.cc
diff --git a/chrome/browser/ui/webui/chrome_url_data_manager_backend.cc b/chrome/browser/ui/webui/chrome_url_data_manager_backend.cc
index 1e12c8e23bcfd57c5f2f024454e6723f5de5b65e..e4adea8f7b4794db69554ea2bcb65dba4c92964f 100644
--- a/chrome/browser/ui/webui/chrome_url_data_manager_backend.cc
+++ b/chrome/browser/ui/webui/chrome_url_data_manager_backend.cc
@@ -10,6 +10,7 @@
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
+#include "base/debug/trace_event.h"
 #include "base/file_util.h"
 #include "base/lazy_instance.h"
 #include "base/memory/ref_counted_memory.h"
@@ -229,6 +230,9 @@ URLRequestChromeJob::~URLRequestChromeJob() {
 }
 
 void URLRequestChromeJob::Start() {
+  TRACE_EVENT_ASYNC_BEGIN1("browser", "DataManager:Request", this, "URL",
+      request_->url().possibly_invalid_spec());
+
   // Start reading asynchronously so that all error reporting and data
   // callbacks happen as they would for network requests.
   MessageLoop::current()->PostTask(
@@ -256,6 +260,7 @@ void URLRequestChromeJob::GetResponseInfo(net::HttpResponseInfo* info) {
 }
 
 void URLRequestChromeJob::DataAvailable(RefCountedMemory* bytes) {
+  TRACE_EVENT_ASYNC_END0("browser", "DataManager:Request", this);

[flackr, 2012/04/12 15:04:05]

If there's any significant amount of work done in this method (i.e. by
CompleteRead) then maybe this signal should be at the end of the method.

   if (bytes) {
     // The request completed, and we have all the data.
     // Clear any IO pending status.