Deprecate Emulation.canEmulate

The method does not specify what parts of the Emulation
domain are actually available for emulation and which are not.

Additionally, it does not seem to have any tests or consumers.
Usually, whether something can be emulated depends on the
target type and platform so this CL deprecates this method
in favor of more granular checks based on target type
and platform and error reporting by individual emulation commands.

Bug: none
Change-Id: I3df1b8dd9571cd99b8ff48f5b402ecc99ce6469e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5310382
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1263441}
diff --git a/third_party/blink/public/devtools_protocol/browser_protocol.pdl b/third_party/blink/public/devtools_protocol/browser_protocol.pdl
index e88bf6b6..0f0f8db0 100644
--- a/third_party/blink/public/devtools_protocol/browser_protocol.pdl
+++ b/third_party/blink/public/devtools_protocol/browser_protocol.pdl
@@ -4053,7 +4053,7 @@
       optional SensorReadingQuaternion quaternion
 
   # Tells whether emulation is supported.
-  command canEmulate
+  deprecated command canEmulate
     returns
       # True if emulation is supported.
       boolean result
@@ -4272,7 +4272,7 @@
   # Overrides default host system timezone with the specified one.
   command setTimezoneOverride
     parameters
-      # The timezone identifier. List of supported timezones: 
+      # The timezone identifier. List of supported timezones:
       # https://source.chromium.org/chromium/chromium/deps/icu.git/+/faee8bc70570192d82d2978a71e2a615788597d1:source/data/misc/metaZones.txt
       # If empty, disables the override and restores default host system timezone.
       string timezoneId