[CodeHealth] Fix leaked, dangling pointer in device::FakeUsbDeviceInfo

FakeUsbDeviceInfo contains a leaked, dangling pointer to
MockUsbMojoDevice. Fix this by:

1. Calling RemoveAllDevices() in FakeUsbDeviceManager's destructor. This
   will clear the scoped_refptrs that FakeUsbDeviceInfo's observers
   have, allowing FakeUsbDeviceInfo to be destroyed.
2. Fixing the member declaration order in tests.

Fixed: 1462085
Change-Id: Iab0ad729b7f8d7fd9179f3c11dcb980acf446712
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4828847
Commit-Queue: Andy Phan <andyphan@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Matt Reynolds <mattreynolds@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1193834}

chrome/browser/extensions/api/usb/chrome_usb_apitest.cc

@@ -83,9 +83,11 @@ class ChromeUsbApiTest : public ExtensionBrowserTest {
             kPolicySetting, extension->url().spec().c_str())));
   }
 
-  device::FakeUsbDeviceManager fake_usb_manager_;
-  scoped_refptr<device::FakeUsbDeviceInfo> fake_device_;
+  // `mock_device_`, `fake_device_`, and `fake_usb_manager_` must be declared in
+  // this order to avoid dangling pointers.
   device::MockUsbMojoDevice mock_device_;
+  scoped_refptr<device::FakeUsbDeviceInfo> fake_device_;
+  device::FakeUsbDeviceManager fake_usb_manager_;
 };
 
 IN_PROC_BROWSER_TEST_F(ChromeUsbApiTest, GetDevicesByPolicy) {

extensions/browser/api/usb/usb_apitest.cc

@@ -149,9 +149,11 @@ class UsbApiTest : public ShellApiTest {
         ->UpdateActiveConfig(fake_device_->guid(), config_value);
   }
 
-  device::FakeUsbDeviceManager fake_usb_manager_;
-  scoped_refptr<device::FakeUsbDeviceInfo> fake_device_;
+  // `mock_device_`, `fake_device_`, and `fake_usb_manager_` must be declared in
+  // this order to avoid dangling pointers.
   device::MockUsbMojoDevice mock_device_;
+  scoped_refptr<device::FakeUsbDeviceInfo> fake_device_;
+  device::FakeUsbDeviceManager fake_usb_manager_;
 };
 
 }  // namespace

services/device/public/cpp/test/fake_usb_device_info.h

@@ -96,7 +96,7 @@ class FakeUsbDeviceInfo : public base::RefCounted<FakeUsbDeviceInfo> {
   void SetDefault();
   mojom::UsbDeviceInfo device_info_;
   base::ObserverList<Observer> observer_list_;
-  raw_ptr<MockUsbMojoDevice, LeakedDanglingUntriaged> mock_device_ = nullptr;
+  raw_ptr<MockUsbMojoDevice> mock_device_ = nullptr;
 };
 
 }  // namespace device

services/device/public/cpp/test/fake_usb_device_manager.cc

@@ -21,7 +21,9 @@ namespace device {
 
 FakeUsbDeviceManager::FakeUsbDeviceManager() {}
 
-FakeUsbDeviceManager::~FakeUsbDeviceManager() {}
+FakeUsbDeviceManager::~FakeUsbDeviceManager() {
+  RemoveAllDevices();
+}
 
 void FakeUsbDeviceManager::EnumerateDevicesAndSetClient(
     mojo::PendingAssociatedRemote<mojom::UsbDeviceManagerClient> client,