ozone: evdev: Switch to char[] for EVIOCGPHYS return

std::string is not used correctly with ioctl() and hence fails to get
the field info. Replace it with C string.

Bug: 827452
Change-Id: Iace6ce24a6405c40a68eeff71c090883b847a46f
Component: Event Device Info, phys
Reviewed-on: https://chromium-review.googlesource.com/1014409Reviewed-by: Michael Spang <spang@chromium.org>
Commit-Queue: Malay Keshav <malaykeshav@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551381}

ui/events/ozone/evdev/event_device_info.cc

@@ -88,10 +88,8 @@ bool GetDeviceIdentifiers(int fd,
 }
 
 void GetDevicePhysInfo(int fd, const base::FilePath& path, std::string* phys) {
-  std::string device_phys;
-  device_phys.reserve(kMaximumDeviceNameLength);
-  if (ioctl(fd, EVIOCGPHYS(kMaximumDeviceNameLength - 1),
-            &device_phys.front()) < 0) {
+  char device_phys[kMaximumDeviceNameLength];
+  if (ioctl(fd, EVIOCGPHYS(kMaximumDeviceNameLength - 1), &device_phys) < 0) {
     PLOG(INFO) << "Failed EVIOCGPHYS (path=" << path.value() << ")";
     return;
   }