[fuchsia] Modify CastRunner's UserAgent string.

Sets the fake build number in the UserAgent string to a different value.

Bug: b/176552416
Bug: 1166790
Change-Id: Icb2ba63fbab785bb28f90b14c84058606abf4404
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2625756
Commit-Queue: David Dorwin <ddorwin@chromium.org>
Reviewed-by: David Dorwin <ddorwin@chromium.org>
Auto-Submit: Kevin Marshall <kmarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843756}

fuchsia/runners/cast/cast_runner.cc

@@ -502,9 +502,9 @@ fuchsia::web::CreateContextParams CastRunner::GetCommonContextParams() {
         fuchsia::web::ContextFeatureFlags::VULKAN;
   }
 
-  // TODO(b/141956135): Fetch this information from the agent.
+  // TODO(crbug.com/1166790): Fetch UserAgent version strings from Agent.
   params.set_user_agent_product("CrKey");
-  params.set_user_agent_version("1.52.000000");
+  params.set_user_agent_version("1.52.999999");
 
   // When tests require that VULKAN be disabled, DRM must also be disabled.
   if (disable_vulkan_for_test_) {