[OH] allow setting `log_filter` via `prefs.json` (#36916)

This PR allows us to set the `log_filter` via `prefs.json` as well as
commandline arguments.

Priority goes commandline > prefs.json > compile-time default.

Testing: I compiled and run servo on an OH device, and then checked the
logs:

```
hdc hilog | tee log | rg 'Set log_filter to'
```

```
05-08 15:25:59.389 55824 55993 D A00000/org.servo.servo/servoshell::prefs: Set log_filter to: Some("debug,geometry=trace")
```

Signed-off-by: Astraea Quinn Skoutelli <astraea.quinn.skoutelli@huawei.com>

2 files changed, 8 insertions, 1 deletions

diff --git a/components/config/prefs.rs b/components/config/prefs.rs
index 96c40c91360..a9ec112e3eb 100644
--- a/components/config/prefs.rs
+++ b/components/config/prefs.rs
@@ -236,6 +236,8 @@ pub struct Preferences {
     /// The user-agent to use for Servo. This can also be set via [`UserAgentPlatform`] in
     /// order to set the value to the default value for the given platform.
     pub user_agent: String,
+
+    pub log_filter: String,
 }
 
 impl Preferences {
@@ -398,6 +400,7 @@ impl Preferences {
             threadpools_webrender_workers_max: 4,
             webgl_testing_context_creation_error: false,
             user_agent: String::new(),
+            log_filter: String::new(),
         }
     }
 }
diff --git a/ports/servoshell/prefs.rs b/ports/servoshell/prefs.rs
index a2efe3bab3b..a3ebda231d0 100644
--- a/ports/servoshell/prefs.rs
+++ b/ports/servoshell/prefs.rs
@@ -428,7 +428,11 @@ pub(crate) fn parse_command_line_arguments(args: Vec<String>) -> ArgumentParsing
     #[cfg(target_env = "ohos")]
     let log_filter = {
         let filters = opt_match.opt_strs("log-filter").join(",");
-        (!filters.is_empty()).then_some(filters)
+        let log_filter = (!filters.is_empty()).then_some(filters).or_else(|| {
+            (!preferences.log_filter.is_empty()).then_some(preferences.log_filter.clone())
+        });
+        log::debug!("Set log_filter to: {:?}", log_filter);
+        log_filter
     };
 
     let mut debug_options = DebugOptions::default();