Add pixel tests for --disable-gpu mode.

On Win/Linux, we will fallback to rendering with SwiftShader.
On other platforms, we will fallback to software rendering with no gpu process.

BUG=783069
TEST=the added tests
R=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: I9a60c71fba04ebdb46d92a5a0442a75f4f236e90
Reviewed-on: https://chromium-review.googlesource.com/764000Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Zhenyao Mo <zmo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515780}

content/test/gpu/gpu_tests/pixel_expectations.py

@@ -25,6 +25,15 @@ class PixelExpectations(GpuTestExpectations):
               ['android'])
     self.Skip('Pixel_CanvasDisplayLinearRGBUnaccelerated2D', ['android'])
 
+    # Tests running with SwiftShader are skipped on platforms where SwiftShader
+    # isn't supported.
+    self.Skip('Pixel_Canvas2DRedBox_SwiftShader',
+        ['mac', 'android', 'chromeos'])
+    self.Skip('Pixel_CSS3DBlueBox_SwiftShader',
+        ['mac', 'android', 'chromeos'])
+    self.Skip('Pixel_WebGLGreenTriangle_AA_Alpha_SwiftShader',
+        ['mac', 'android', 'chromeos'])
+
     self.Fail('Pixel_ScissorTestWithPreserveDrawingBuffer',
         ['android'], bug=521588)
 
@@ -74,3 +83,10 @@ class PixelExpectations(GpuTestExpectations):
     self.Fail('Pixel_WebGLGreenTriangle_NonChromiumImage_NoAA_NoAlpha',
         ['highsierra', ('intel', 0xa2e)], bug=774809)
 
+    # New tests. Remove entries after completing first run on bots.
+    self.Fail('Pixel_Canvas2DRedBox_NoGpuProcess', bug=783069)
+    self.Fail('Pixel_CSS3DBlueBox_NoGpuProcess', bug=783069)
+    self.Fail('Pixel_Canvas2DRedBox_SwiftShader', ['win', 'linux'], bug=783069)
+    self.Fail('Pixel_CSS3DBlueBox_SwiftShader', ['win', 'linux'], bug=783069)
+    self.Fail('Pixel_WebGLGreenTriangle_AA_Alpha_SwiftShader',
+        ['win', 'linux'], bug=783069)

content/test/gpu/gpu_tests/pixel_integration_test.py

@@ -96,6 +96,10 @@ class PixelIntegrationTest(
     pages = pixel_test_pages.DefaultPages(name)
     pages += pixel_test_pages.GpuRasterizationPages(name)
     pages += pixel_test_pages.ExperimentalCanvasFeaturesPages(name)
+    pages += pixel_test_pages.NoGpuProcessPages(name)
+    # The following pages should run only on platforms where SwiftShader is
+    # enabled. They are skipped on other platforms through test expectations.
+    pages += pixel_test_pages.SwiftShaderPages(name)
     if sys.platform.startswith('darwin'):
       pages += pixel_test_pages.MacSpecificPages(name)
     if sys.platform.startswith('win'):

content/test/gpu/gpu_tests/pixel_test_pages.py

@@ -523,6 +523,54 @@ def ExperimentalCanvasFeaturesPages(base_name):
 ]
 
 
+# Only add these tests on platforms where SwiftShader is enabled.
+# Currently this is Windows and Linux.
+def SwiftShaderPages(base_name):
+  browser_args = ['--disable-gpu']
+  suffix = "_SwiftShader"
+  return [
+    PixelTestPage(
+      'pixel_canvas2d.html',
+      base_name + '_Canvas2DRedBox' + suffix,
+      test_rect=[0, 0, 300, 300],
+      revision=1,
+      browser_args=browser_args),
+
+    PixelTestPage(
+      'pixel_css3d.html',
+      base_name + '_CSS3DBlueBox' + suffix,
+      test_rect=[0, 0, 300, 300],
+      revision=1,
+      browser_args=browser_args),
+
+    PixelTestPage(
+      'pixel_webgl_aa_alpha.html',
+      base_name + '_WebGLGreenTriangle_AA_Alpha' + suffix,
+      test_rect=[0, 0, 300, 300],
+      revision=1,
+      browser_args=browser_args),
+  ]
+
+# Test rendering where GPU process is blocked.
+def NoGpuProcessPages(base_name):
+  browser_args = ['--disable-gpu', '--disable-software-rasterizer']
+  suffix = "_NoGpuProcess"
+  return [
+    PixelTestPage(
+      'pixel_canvas2d.html',
+      base_name + '_Canvas2DRedBox' + suffix,
+      test_rect=[0, 0, 300, 300],
+      revision=1,
+      browser_args=browser_args),
+
+    PixelTestPage(
+      'pixel_css3d.html',
+      base_name + '_CSS3DBlueBox' + suffix,
+      test_rect=[0, 0, 300, 300],
+      revision=1,
+      browser_args=browser_args),
+  ]
+
 # Pages that should be run with various macOS specific command line
 # arguments.
 def MacSpecificPages(base_name):