[TaskScheduler]: Use ScopedBlockingCall to mark blocking tasks.

This CL uses ScopedBlockingCall to mark blocking calls in /device.

This CL was created by replacing calls to AssertBlockingAllowed()
with instantiations of ScopedBlockingCall(MAY_BLOCK).
I kindly ask the reviewer to make sure of the following:
  - ScopedBlockingCall is instantiated in a scope with minimal CPU usage.
    If this is not the case, ScopedBlockingCall should be instantiated
    closer to the blocking call. See scoped_blocking_call.h for more
    info. Please let me know when/where the blocking call happens if this needs
    to be changed.
  - Parameter |blocking_type| matches expectation (MAY_BLOCK/WILL_BLOCK). See
    BlockingType for more info. While I assumed MAY_BLOCK by default, that might
    not be the best fit if we know that this callsite is guaranteed to block.
  - The ScopedBlockingCall's scope covers the entirety of the blocking operation
    previously asserted against by the AssertBlockingAllowed().

This CL was uploaded by git cl split.

R=reillyg@chromium.org

Bug: 874080
Change-Id: I1bad5e82040c40aa770c36d3825dfc14dd9aad0f
Reviewed-on: https://chromium-review.googlesource.com/1191813Reviewed-by: Reilly Grant <reillyg@chromium.org>
Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592887}

device/base/device_monitor_linux.cc

@@ -10,7 +10,7 @@
 #include "base/bind.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
-#include "base/threading/thread_restrictions.h"
+#include "base/threading/scoped_blocking_call.h"
 #include "device/udev_linux/udev.h"
 
 namespace device {
@@ -28,7 +28,7 @@ base::LazyInstance<DeviceMonitorLinux>::Leaky g_device_monitor_linux =
 }  // namespace
 
 DeviceMonitorLinux::DeviceMonitorLinux() : monitor_fd_(-1) {
-  base::AssertBlockingAllowed();
+  base::ScopedBlockingCall scoped_blocking_call(base::BlockingType::MAY_BLOCK);
 
   udev_.reset(udev_new());
   if (!udev_) {

device/serial/serial_device_enumerator_linux.cc

@@ -11,7 +11,7 @@
 
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
-#include "base/threading/thread_restrictions.h"
+#include "base/threading/scoped_blocking_call.h"
 
 namespace device {
 
@@ -41,7 +41,7 @@ SerialDeviceEnumeratorLinux::~SerialDeviceEnumeratorLinux() = default;
 
 std::vector<mojom::SerialDeviceInfoPtr>
 SerialDeviceEnumeratorLinux::GetDevices() {
-  base::AssertBlockingAllowed();
+  base::ScopedBlockingCall scoped_blocking_call(base::BlockingType::MAY_BLOCK);
 
   std::vector<mojom::SerialDeviceInfoPtr> devices;
   ScopedUdevEnumeratePtr enumerate(udev_enumerate_new(udev_.get()));

device/serial/serial_device_enumerator_mac.cc

@@ -22,7 +22,7 @@
 #include "base/strings/pattern.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
-#include "base/threading/thread_restrictions.h"
+#include "base/threading/scoped_blocking_call.h"
 
 namespace device {
 
@@ -104,7 +104,8 @@ int Clamp(int value, int min, int max) {
 // about the devices than the old method.
 std::vector<mojom::SerialDeviceInfoPtr> GetDevicesNew() {
   std::vector<mojom::SerialDeviceInfoPtr> devices;
-
+  
+  base::ScopedBlockingCall scoped_blocking_call(base::BlockingType::MAY_BLOCK);
   // Make a service query to find all serial devices.
   CFMutableDictionaryRef matchingDict =
       IOServiceMatching(kIOSerialBSDServiceValue);
@@ -182,6 +183,7 @@ std::vector<mojom::SerialDeviceInfoPtr> GetDevicesOld() {
   valid_patterns.insert("/dev/tty.*");
   valid_patterns.insert("/dev/cu.*");
 
+  base::ScopedBlockingCall scoped_blocking_call(base::BlockingType::MAY_BLOCK);
   std::vector<mojom::SerialDeviceInfoPtr> devices;
   base::FileEnumerator enumerator(kDevRoot, false, kFilesAndSymLinks);
   do {
@@ -217,8 +219,6 @@ SerialDeviceEnumeratorMac::~SerialDeviceEnumeratorMac() {}
 
 std::vector<mojom::SerialDeviceInfoPtr>
 SerialDeviceEnumeratorMac::GetDevices() {
-  base::AssertBlockingAllowed();
-
   std::vector<mojom::SerialDeviceInfoPtr> devices = GetDevicesNew();
   std::vector<mojom::SerialDeviceInfoPtr> old_devices = GetDevicesOld();
 

device/serial/serial_device_enumerator_win.cc

@@ -18,7 +18,7 @@
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
-#include "base/threading/thread_restrictions.h"
+#include "base/threading/scoped_blocking_call.h"
 #include "base/win/registry.h"
 #include "third_party/re2/src/re2/re2.h"
 
@@ -93,6 +93,7 @@ int Clamp(int value, int min, int max) {
 std::vector<mojom::SerialDeviceInfoPtr> GetDevicesNew() {
   std::vector<mojom::SerialDeviceInfoPtr> devices;
 
+  base::ScopedBlockingCall scoped_blocking_call(base::BlockingType::MAY_BLOCK);
   // Make a device interface query to find all serial devices.
   HDEVINFO dev_info =
       SetupDiGetClassDevs(&GUID_DEVCLASS_PORTS, 0, 0, DIGCF_PRESENT);
@@ -143,6 +144,7 @@ std::vector<mojom::SerialDeviceInfoPtr> GetDevicesNew() {
 // enumerating serial devices (searching the registry). This old method gives
 // less information about the devices than the new method.
 std::vector<mojom::SerialDeviceInfoPtr> GetDevicesOld() {
+  base::ScopedBlockingCall scoped_blocking_call(base::BlockingType::MAY_BLOCK);
   base::win::RegistryValueIterator iter_key(
       HKEY_LOCAL_MACHINE, L"HARDWARE\\DEVICEMAP\\SERIALCOMM\\");
   std::vector<mojom::SerialDeviceInfoPtr> devices;
@@ -168,8 +170,6 @@ SerialDeviceEnumeratorWin::~SerialDeviceEnumeratorWin() {}
 
 std::vector<mojom::SerialDeviceInfoPtr>
 SerialDeviceEnumeratorWin::GetDevices() {
-  base::AssertBlockingAllowed();
-
   std::vector<mojom::SerialDeviceInfoPtr> devices = GetDevicesNew();
   std::vector<mojom::SerialDeviceInfoPtr> old_devices = GetDevicesOld();