feat(DASH): Remove MIN_UPDATE_PERIOD_ to achieve better latency in Li…

…ve (shaka-project#5286)

Many LL streams use 2 seconds segments, so we have to ensure that these
streams work correctly.

lib/dash/dash_parser.js

@@ -1416,7 +1416,6 @@ shaka.dash.DashParser = class {
     }
 
     const finalDelay = Math.max(
-        shaka.dash.DashParser.MIN_UPDATE_PERIOD_,
         this.updatePeriod_ - offset,
         this.averageUpdateDuration_.getEstimate());
 
@@ -1900,16 +1899,6 @@ shaka.dash.DashParser = class {
 };
 
 
-/**
- * Contains the minimum amount of time, in seconds, between manifest update
- * requests.
- *
- * @private
- * @const {number}
- */
-shaka.dash.DashParser.MIN_UPDATE_PERIOD_ = 3;
-
-
 /**
  * @typedef {
  *   function(!Array.<string>, ?number, ?number, boolean):

test/dash/dash_parser_live_unit.js

@@ -673,10 +673,9 @@ describe('DashParser Live', () => {
     fakeNetEngine.setResponseText('dummy://foo', manifestText);
     await parser.start('dummy://foo', playerInterface);
 
-    const waitTime = shaka.dash.DashParser['MIN_UPDATE_PERIOD_'];
     expect(tickAfter).toHaveBeenCalledTimes(1);
     const delay = tickAfter.calls.mostRecent().args[0];
-    expect(delay).toBe(waitTime);
+    expect(delay).toBe(0);
   });
 
   it('does not update when @minimumUpdatePeriod is missing', async () => {
@@ -701,8 +700,7 @@ describe('DashParser Live', () => {
       '<SegmentTemplate startNumber="1" media="s$Number$.mp4" duration="2" />',
     ];
     const extraWaitTime = 15.0;
-    const idealUpdateTime = shaka.dash.DashParser['MIN_UPDATE_PERIOD_'];
-    const manifestText = makeSimpleLiveManifestText(lines, idealUpdateTime);
+    const manifestText = makeSimpleLiveManifestText(lines, 3);
 
     let now = 0;
     Date.now = () => now;