gpu: Allow framebuffers with mixed samples if the hw supports it

gpu/command_buffer/service/framebuffer_manager.cc

Index: gpu/command_buffer/service/framebuffer_manager.cc
diff --git a/gpu/command_buffer/service/framebuffer_manager.cc b/gpu/command_buffer/service/framebuffer_manager.cc
index c353136440281758735d8c74fec7a33b9c84b9af..54a931cdcdc35dc07f3d6f3eb6b53071b90e0de2 100644
--- a/gpu/command_buffer/service/framebuffer_manager.cc
+++ b/gpu/command_buffer/service/framebuffer_manager.cc
@@ -579,6 +579,11 @@ GLenum Framebuffer::IsPossiblyComplete(const FeatureInfo* feature_info) const {
   GLsizei width = -1;
   GLsizei height = -1;
   GLsizei samples = -1;
+  const bool kSamplesMustMatch =
+      feature_info->context_type() == CONTEXT_TYPE_WEBGL1 ||
+      feature_info->context_type() == CONTEXT_TYPE_WEBGL2 ||
+      !feature_info->feature_flags().chromium_framebuffer_mixed_samples;
+
   for (AttachmentMap::const_iterator it = attachments_.begin();
        it != attachments_.end(); ++it) {
     GLenum attachment_type = it->first;
@@ -603,13 +608,16 @@ GLenum Framebuffer::IsPossiblyComplete(const FeatureInfo* feature_info) const {
       // behaviors across platforms.
       return GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS_EXT;
     }
-    if (samples < 0) {
-      samples = attachment->samples();
-    } else if (attachment->samples() != samples) {
-      // It's possible that the specified samples isn't the actual samples a
-      // GL implementation uses, but we always return INCOMPLETE_MULTISAMPLE
-      // here to ensure consistent behaviors across platforms.
-      return GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE;
+
+    if (kSamplesMustMatch) {
+      if (samples < 0) {
+        samples = attachment->samples();
+      } else if (attachment->samples() != samples) {
+        // It's possible that the specified samples isn't the actual samples a
+        // GL implementation uses, but we always return INCOMPLETE_MULTISAMPLE
+        // here to ensure consistent behaviors across platforms.
+        return GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE;
+      }
     }
     if (!attachment->CanRenderTo(feature_info)) {
       return GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;