Increase gtest shard timeout for angle_deqp_gles2_gles_tests

gtest started to shard in a different way when we switched
from 7 Android devices to 1, so one of the 256 test batches
started to intermittenly time out.

BUG=670879
TBR=kbr@chromium.org

Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: I8b5594dac3f4269a8f8d03e6be715af968aa81ea
Reviewed-on: https://chromium-review.googlesource.com/577918
Commit-Queue: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488010}

content/test/gpu/generate_buildbot_json.py

@@ -1057,7 +1057,10 @@ COMMON_GTESTS = {
       '--test-launcher-batch-limit=400',
       '--deqp-egl-display-type=angle-gles'
     ],
-    'android_args': ['--enable-xml-result-parsing']
+    'android_args': [
+      '--enable-xml-result-parsing',
+      '--shard-timeout=300'
+    ],
   },
 
   'angle_deqp_gles3_gles_tests': {

testing/buildbot/chromium.gpu.fyi.json

@@ -755,7 +755,8 @@
     "gtest_tests": [
       {
         "args": [
-          "--enable-xml-result-parsing"
+          "--enable-xml-result-parsing",
+          "--shard-timeout=300"
         ],
         "name": "angle_deqp_gles2_gles_tests",
         "swarming": {