Fix MSAA on windows

MSAA would brake on windows because skia creates a BGRA8 internal format render
buffer, which we didn't support on windows.

We were turning on BGRA8_EXT for render buffers when we had
https://www.opengl.org/registry/specs/EXT/bgra.txt, this is a desktop spec that doesn't mention BGRA8_EXT
for render buffers, but we're assuming that it should support it.

I've added the condition that BGRA8 is supported for ANGLE as well as GL_EXT_bgra, and a couple test
to confirm this.

BUG=460567

Review URL: https://codereview.chromium.org/947653002

Cr-Commit-Position: refs/heads/master@{#317958}

2 files changed, 22 insertions, 2 deletions

diff --git a/gpu/command_buffer/service/feature_info.cc b/gpu/command_buffer/service/feature_info.cc
index 803b121..79cc361 100644
--- a/gpu/command_buffer/service/feature_info.cc
+++ b/gpu/command_buffer/service/feature_info.cc
@@ -471,7 +471,9 @@ void FeatureInfo::InitializeFeatures() {
     enable_texture_format_bgra8888 = true;
   }
 
-  if (extensions.Contains("GL_EXT_bgra")) {
+  // Only desktop GL extension GL_EXT_bgra or ANGLE guarantee that we can
+  // allocate a renderbuffer with this format.
+  if (extensions.Contains("GL_EXT_bgra") || gl_version_info_->is_angle) {
     enable_render_buffer_bgra = true;
   }
 
diff --git a/gpu/command_buffer/service/feature_info_unittest.cc b/gpu/command_buffer/service/feature_info_unittest.cc
index 8455be6..177ef10 100644
--- a/gpu/command_buffer/service/feature_info_unittest.cc
+++ b/gpu/command_buffer/service/feature_info_unittest.cc
@@ -576,7 +576,7 @@ TEST_F(FeatureInfoTest, InitializeEXT_texture_storage_half_float) {
       GL_LUMINANCE_ALPHA16F_EXT));
 }
 
-// Check how to handle ES, texture_storage and BGRA combination; 8 tests.
+// Check how to handle ES, texture_storage and BGRA combination; 10 tests.
 
 // 1- ES2 + GL_EXT_texture_storage -> GL_EXT_texture_storage (and no
 // GL_EXT_texture_format_BGRA8888 - we don't claim to handle GL_BGRA8 in
@@ -658,6 +658,24 @@ TEST_F(FeatureInfoTest, InitializeGLES3_texture_storage) {
               Not(HasSubstr("GL_EXT_texture_format_BGRA8888")));
 }
 
+// 9- ANGLE will add the GL_CHROMIUM_renderbuffer_format_BGRA8888 extension and
+// the GL_BGRA8_EXT render buffer format.
+TEST_F(FeatureInfoTest, InitializeWithANGLE_BGRA8) {
+  SetupInitExpectationsWithGLVersion("", kGLRendererStringANGLE, "");
+  EXPECT_TRUE(info_->gl_version_info().is_angle);
+  EXPECT_THAT(info_->extensions(),
+              HasSubstr("GL_CHROMIUM_renderbuffer_format_BGRA8888"));
+  EXPECT_TRUE(info_->validators()->render_buffer_format.IsValid(GL_BGRA8_EXT));
+}
+
+// 10- vanilla opengl es means no GL_CHROMIUM_renderbuffer_format_BGRA8888
+TEST_F(FeatureInfoTest,
+       InitializeGLES2_no_CHROMIUM_renderbuffer_format_BGRA8888) {
+  SetupInitExpectationsWithGLVersion("", "", "OpenGL ES 2.0");
+  EXPECT_THAT(info_->extensions(),
+              Not(HasSubstr("GL_CHROMIUM_renderbuffer_format_BGRA8888")));
+}
+
 TEST_F(FeatureInfoTest, InitializeARB_texture_float) {
   SetupInitExpectations("GL_ARB_texture_float");
   EXPECT_TRUE(info_->feature_flags().chromium_color_buffer_float_rgba);