Fix TaskmanagerIoThreadHelper bug.

Deleting the TaskManagerIoThreadHelper should cancel any pending
OnMultipleBytesReadIO calls. If it doesn't, we can sometimes fail the
DCHECK(!bytes_read_buffer_.empty()); check.

BUG=None
TEST=TaskManagerOOPIFBrowserTest.LeavePageWithCrossSiteIframes/0

Review URL: https://codereview.chromium.org/1918423002

Cr-Commit-Position: refs/heads/master@{#389889}

chrome/browser/task_management/sampling/task_manager_io_thread_helper.cc

@@ -59,7 +59,7 @@ void TaskManagerIoThreadHelper::OnRawBytesRead(const net::URLRequest& request,
     g_io_thread_helper->OnNetworkBytesRead(request, bytes_read);
 }
 
-TaskManagerIoThreadHelper::TaskManagerIoThreadHelper() {
+TaskManagerIoThreadHelper::TaskManagerIoThreadHelper() : weak_factory_(this) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
 }
 
@@ -67,18 +67,14 @@ TaskManagerIoThreadHelper::~TaskManagerIoThreadHelper() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
 }
 
-// static
 void TaskManagerIoThreadHelper::OnMultipleBytesReadIO() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
 
-  if (!g_io_thread_helper)
-    return;
-
-  DCHECK(!g_io_thread_helper->bytes_read_buffer_.empty());
+  DCHECK(!bytes_read_buffer_.empty());
 
   std::vector<BytesReadParam>* bytes_read_buffer =
       new std::vector<BytesReadParam>();
-  g_io_thread_helper->bytes_read_buffer_.swap(*bytes_read_buffer);
+  bytes_read_buffer_.swap(*bytes_read_buffer);
 
   content::BrowserThread::PostTask(
       content::BrowserThread::UI,
@@ -114,9 +110,9 @@ void TaskManagerIoThreadHelper::OnNetworkBytesRead(
     // delayed TaskManagerIoThreadHelper::OnMultipleBytesReadIO() process them
     // after one second from now.
     content::BrowserThread::PostDelayedTask(
-        content::BrowserThread::IO,
-        FROM_HERE,
-        base::Bind(TaskManagerIoThreadHelper::OnMultipleBytesReadIO),
+        content::BrowserThread::IO, FROM_HERE,
+        base::Bind(&TaskManagerIoThreadHelper::OnMultipleBytesReadIO,
+                   weak_factory_.GetWeakPtr()),
         base::TimeDelta::FromSeconds(1));
   }
 

chrome/browser/task_management/sampling/task_manager_io_thread_helper.h

@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "base/macros.h"
+#include "base/memory/weak_ptr.h"
 
 namespace net {
 class URLRequest;
@@ -78,7 +79,7 @@ class TaskManagerIoThreadHelper {
 
   // We gather multiple notifications on the IO thread in one second before a
   // call is made to the following function to start the processing.
-  static void OnMultipleBytesReadIO();
+  void OnMultipleBytesReadIO();
 
   // This will update the task manager with the network bytes read.
   void OnNetworkBytesRead(const net::URLRequest& request, int64_t bytes_read);
@@ -87,6 +88,8 @@ class TaskManagerIoThreadHelper {
   // of bytes read from URLRequests.
   std::vector<BytesReadParam> bytes_read_buffer_;
 
+  base::WeakPtrFactory<TaskManagerIoThreadHelper> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(TaskManagerIoThreadHelper);
 };