Standardize "gpu_times" metric names and add GPU rasterization versions.

The GPU Times metric event names have been standardized to match the
names for other metrics. GPU Rasterization versions have also been
added for both GPU times tests. Here is the list of test names:
  gpu_times.gpu_rasterization.key_mobile_sites_smooth
  gpu_times.gpu_rasterization.top_25_smooth
  gpu_times.key_mobile_sites_smooth
  gpu_times.top_25_smooth

R=vmiura@chromium.org
BUG=none
test=trybots

Review URL: https://codereview.chromium.org/875473003

Cr-Commit-Position: refs/heads/master@{#313825}

tools/perf/benchmarks/gpu_times.py

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
+from benchmarks import silk_flags
 from metrics import gpu_timeline
 import page_sets
 from telemetry import benchmark
@@ -31,7 +32,37 @@ class GPUTimesKeyMobileSites(_GPUTimes):
   """Measures GPU timeline metric on key mobile sites."""
   page_set = page_sets.KeyMobileSitesSmoothPageSet
 
+  @classmethod
+  def Name(cls):
+    return 'gpu_times.key_mobile_sites_smooth'
+
+@benchmark.Enabled('android')
+class GPUTimesGpuRasterizationKeyMobileSites(_GPUTimes):
+  """Measures GPU timeline metric on key mobile sites with GPU rasterization.
+  """
+  page_set = page_sets.KeyMobileSitesSmoothPageSet
+  def CustomizeBrowserOptions(self, options):
+    silk_flags.CustomizeBrowserOptionsForGpuRasterization(options)
+
+  @classmethod
+  def Name(cls):
+    return 'gpu_times.gpu_rasterization.key_mobile_sites_smooth'
 
 class GPUTimesTop25Sites(_GPUTimes):
   """Measures GPU timeline metric for the top 25 sites."""
   page_set = page_sets.Top25SmoothPageSet
+
+  @classmethod
+  def Name(cls):
+    return 'gpu_times.top_25_smooth'
+
+class GPUTimesGpuRasterizationTop25Sites(_GPUTimes):
+  """Measures GPU timeline metric for the top 25 sites with GPU rasterization.
+  """
+  page_set = page_sets.Top25SmoothPageSet
+  def CustomizeBrowserOptions(self, options):
+    silk_flags.CustomizeBrowserOptionsForGpuRasterization(options)
+
+  @classmethod
+  def Name(cls):
+    return 'gpu_times.gpu_rasterization.top_25_smooth'