Increase trace buffer size of power.desktop to 300mb

The 'abcnews' pageset was hitting this limit and failing perf runs.

R=sullivan@chromium.org

Bug: 2052598
Change-Id: If7d36791611dc42cacff5e083f7d38fb83a61cd1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2146086
Auto-Submit: oysteine <oysteine@chromium.org>
Commit-Queue: Annie Sullivan <sullivan@chromium.org>
Reviewed-by: Annie Sullivan <sullivan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#758512}

tools/perf/benchmarks/power.py

@@ -30,6 +30,7 @@ class PowerDesktop(perf_benchmark.PerfBenchmark):
     options = timeline_based_measurement.Options(category_filter)
     options.config.enable_chrome_trace = True
     options.config.enable_cpu_trace = True
+    options.config.chrome_trace_config.SetTraceBufferSizeInKb(300 * 1024)
     options.SetTimelineBasedMetrics(['tbmv2:cpuTimeMetric',
                                      'tbmv3:console_error_metric'])
     return options