Remove an obsolete comment in pointer_id.h

We don't need to add 'Web' prefix to symbols in public/common/.

No-Try: true
Change-Id: I2a9902e045edac25280451c071a42722dbd95843
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2623568
Auto-Submit: Kent Tamura <tkent@chromium.org>
Commit-Queue: Mustaq Ahmed <mustaq@chromium.org>
Reviewed-by: Mustaq Ahmed <mustaq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842522}

third_party/blink/public/common/input/pointer_id.h

@@ -9,8 +9,6 @@
 
 namespace blink {
 
-// TODO(tkent): Rename this to WebPointerID to follow the naming convention
-// in blink/public/.
 using PointerId = std::int32_t;
 
 }  // namespace blink