[CE] Correct logic of DefaultEventHandler in HTMLUserMediaElement

Ensure that HTMLUserMediaElement does not initiate multiple concurrent
media stream requests. Previously, rapid user activations could trigger
overlapping requests before the initial one had completed.

Additionally, the activation logic was updated to use the base
capability element's activation handler, ensuring that permission
checks and media requests are correctly synchronized with user events.

Fixed: 5003039

Change-Id: I84f733a590d24d0fa60c08a49fc3a19b9314c695
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7734929
Reviewed-by: Joey Arhar <jarhar@chromium.org>
Commit-Queue: Thomas Nguyen <tungnh@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1616082}

Author: Thomas Nguyen

html/semantics/permission-element/usermedia/set-constraints-combinations.tentative.html

@@ -78,14 +78,14 @@
         // should_trigger is true if the element has at least one permission descriptor.
         const should_trigger = (type !== null) || (video === true) || (audio === true);
 
-        // Wait for PEPC registration
-        await new Promise(r => t.step_timeout(r, 100));
+        // Wait until the element is clickable.
+        await new Promise(r => t.step_timeout(r, 600));
 
         if (should_trigger) {
-          await test_driver.bless("click", () => usermedia.click());
+          await test_driver.click(usermedia);
           await stream_promise;
         } else {
-          await test_driver.bless("click", () => usermedia.click());
+          await test_driver.click(usermedia);
           // Wait a bit to ensure no stream event is fired
           await new Promise(r => t.step_timeout(r, 200));
         }

html/semantics/permission-element/usermedia/usermedia-constraints-descriptors.tentative.html

@@ -27,6 +27,8 @@
     }
 
     await Promise.all(permissions);
+    // Wait until the element is clickable.
+    await new Promise(resolve => t.step_timeout(resolve, 600));
     await test_driver.click(usermedia);
 
     const e = await stream_promise;

html/semantics/permission-element/usermedia/usermedia-no-constraints.tentative.html

@@ -23,6 +23,8 @@
     test_driver.set_permission({name: 'microphone'}, 'granted')
   ]);
 
+  // Wait until the element is clickable.
+  await new Promise(resolve => t.step_timeout(resolve, 600));
   await test_driver.click(usermedia);
 
   // Wait a bit to see if 'onstream' fires.
@@ -48,6 +50,8 @@
     test_driver.set_permission({name: 'microphone'}, 'granted')
   ]);
 
+  // Wait until the element is clickable.
+  await new Promise(resolve => t.step_timeout(resolve, 600));
   await test_driver.click(usermedia);
 
   // Wait a bit to see if 'onstream' fires.
@@ -68,6 +72,8 @@
   });
 
   await test_driver.set_permission({name: 'camera'}, 'granted');
+  // Wait until the element is clickable.
+  await new Promise(resolve => t.step_timeout(resolve, 600));
   await test_driver.click(usermedia);
 
   const e = await stream_promise;