Fix WeakPtrFactory member ordering in device

Changing in the intialization order of WeakPtrFactory such that all
member variables should appear before the WeakPtrFactory to ensure
that any WeakPtrs to Controller are invalidated before its members
variable's destructors are executed, rendering them invalid.

BUG=303818

Review URL: https://codereview.chromium.org/791743006

Cr-Commit-Position: refs/heads/master@{#308090}

device/usb/usb_device_handle_impl.cc

@@ -479,8 +479,8 @@ UsbDeviceHandleImpl::UsbDeviceHandleImpl(scoped_refptr<UsbContext> context,
       handle_(handle),
       config_(config),
       context_(context),
-      weak_factory_(this),
-      task_runner_(base::ThreadTaskRunnerHandle::Get()) {
+      task_runner_(base::ThreadTaskRunnerHandle::Get()),
+      weak_factory_(this) {
   DCHECK(handle) << "Cannot create device with NULL handle.";
 }
 

device/usb/usb_device_handle_impl.h

@@ -149,10 +149,10 @@ class UsbDeviceHandleImpl : public UsbDeviceHandle {
   // before this handle.
   scoped_refptr<UsbContext> context_;
 
-  base::WeakPtrFactory<UsbDeviceHandleImpl> weak_factory_;
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
   base::ThreadChecker thread_checker_;
+  base::WeakPtrFactory<UsbDeviceHandleImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(UsbDeviceHandleImpl);
 };