gpu: Clarify sized texture format is available only if ES3 context or immutable texture is supported

gpu/command_buffer/service/texture_manager.cc

Index: gpu/command_buffer/service/texture_manager.cc
diff --git a/gpu/command_buffer/service/texture_manager.cc b/gpu/command_buffer/service/texture_manager.cc
index 0ab416a494992fb4217fb1430d632b767d676489..a16ea7529bc50f3272e2124e3f0195474e6aa852 100644
--- a/gpu/command_buffer/service/texture_manager.cc
+++ b/gpu/command_buffer/service/texture_manager.cc
@@ -231,6 +231,8 @@ class FormatTypeValidator {
         {GL_DEPTH24_STENCIL8, GL_DEPTH_STENCIL, GL_UNSIGNED_INT_24_8},
         {GL_DEPTH32F_STENCIL8, GL_DEPTH_STENCIL,
          GL_FLOAT_32_UNSIGNED_INT_24_8_REV},
+        // Exposed by GL_APPLE_texture_format_BGRA8888
+        {GL_BGRA8_EXT, GL_BGRA_EXT, GL_UNSIGNED_BYTE},
     };
 
     for (size_t ii = 0; ii < arraysize(kSupportedFormatTypes); ++ii) {
@@ -308,6 +310,24 @@ GLenum GetSwizzleForChannel(GLenum channel,
   }
 }
 
+bool SizedFormatAvailable(const FeatureInfo* feature_info,
+                          bool immutable,
+                          GLenum internal_format) {
+  if (immutable)
+    return true;
+
+  // TODO(dshwang): check if it's possible to remove
+  // CHROMIUM_color_buffer_float_rgb. crbug.com/329605
+  if ((feature_info->feature_flags().chromium_color_buffer_float_rgb &&
+       internal_format == GL_RGB32F) ||
+      (feature_info->feature_flags().chromium_color_buffer_float_rgba &&
+       internal_format == GL_RGBA32F)) {
+    return true;
+  }

[dshwang, 2016/10/14 12:03:34]

following test failed.
https://www.khronos.org/registry/webgl/sdk/tests/conformance/extensions/oes-t...

It's because https://bugs.chromium.org/p/chromium/issues/detail?id=329605 added
CHROMIUM_color_buffer_float_rgb extensions;
https://cs.chromium.org/chromium/src/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_c...
, which allows TexImage*(GL_RGB32F) in ES2 context.

I'm not fully understand why it's needed. kbr@, do you have some clue?

[Ken Russell (switch to Gerrit), 2016/10/20 04:59:40]

Sorry, I don't remember. The ultimate goal was to enable rendering to these
floating-point textures in WebGL 1.0 via an extension, but I don't remember the
reason for this direction.

+
+  return feature_info->IsES3Enabled();
+}
+
 // A 32-bit and 64-bit compatible way of converting a pointer to a GLuint.
 GLuint ToGLuint(const void* ptr) {
   return static_cast<GLuint>(reinterpret_cast<size_t>(ptr));
@@ -601,9 +621,8 @@ bool Texture::CanRenderWithSampler(const FeatureInfo* feature_info,
       // TODO(zmo): The assumption that compressed textures are all filterable
       // may not be true in the future.
     } else {
-      if (!Texture::TextureFilterable(feature_info,
-                                      first_level.internal_format,
-                                      first_level.type)) {
+      if (!Texture::TextureFilterable(feature_info, first_level.internal_format,
+                                      first_level.type, immutable_)) {
         return false;
       }
     }
@@ -729,9 +748,10 @@ bool Texture::CanGenerateMipmaps(const FeatureInfo* feature_info) const {
     return false;
   }
 
-  if (!Texture::ColorRenderable(feature_info, base.internal_format) ||
-      !Texture::TextureFilterable(
-          feature_info, base.internal_format, base.type)) {
+  if (!Texture::ColorRenderable(feature_info, base.internal_format,
+                                immutable_) ||
+      !Texture::TextureFilterable(feature_info, base.internal_format, base.type,
+                                  immutable_)) {
     return false;
   }
 
@@ -808,19 +828,24 @@ bool Texture::TextureMipComplete(const Texture::LevelInfo& base_level_face,
 
 // static
 bool Texture::ColorRenderable(const FeatureInfo* feature_info,
-                              GLenum internal_format) {
+                              GLenum internal_format,
+                              bool immutable) {
   if (feature_info->validators()->texture_unsized_internal_format.IsValid(
       internal_format)) {
     return true;
   }
-  return feature_info->validators()->
-      texture_sized_color_renderable_internal_format.IsValid(internal_format);
+
+  return SizedFormatAvailable(feature_info, immutable, internal_format) &&
+         feature_info->validators()
+             ->texture_sized_color_renderable_internal_format.IsValid(
+                 internal_format);
 }
 
 // static
 bool Texture::TextureFilterable(const FeatureInfo* feature_info,
                                 GLenum internal_format,
-                                GLenum type) {
+                                GLenum type,
+                                bool immutable) {
   if (feature_info->validators()->texture_unsized_internal_format.IsValid(
       internal_format)) {
     switch (type) {
@@ -833,8 +858,10 @@ bool Texture::TextureFilterable(const FeatureInfo* feature_info,
         return true;
     }
   }
-  return feature_info->validators()->
-      texture_sized_texture_filterable_internal_format.IsValid(internal_format);
+  return SizedFormatAvailable(feature_info, immutable, internal_format) &&
+         feature_info->validators()
+             ->texture_sized_texture_filterable_internal_format.IsValid(
+                 internal_format);
 }
 
 void Texture::SetLevelClearedRect(GLenum target,
@@ -1711,15 +1738,15 @@ bool Texture::CanRenderTo(const FeatureInfo* feature_info, GLint level) const {
          level < static_cast<GLint>(face_infos_[0].level_infos.size()));
   GLenum internal_format = face_infos_[0].level_infos[level].internal_format;
   bool color_renderable =
-      ((feature_info->validators()->texture_unsized_internal_format.
-            IsValid(internal_format) &&
-        internal_format != GL_ALPHA &&
-        internal_format != GL_LUMINANCE &&
+      ((feature_info->validators()->texture_unsized_internal_format.IsValid(
+            internal_format) &&
+        internal_format != GL_ALPHA && internal_format != GL_LUMINANCE &&
         internal_format != GL_LUMINANCE_ALPHA &&
         internal_format != GL_SRGB_EXT) ||
-       feature_info->validators()->
-           texture_sized_color_renderable_internal_format.IsValid(
-               internal_format));
+       (SizedFormatAvailable(feature_info, immutable_, internal_format) &&
+        feature_info->validators()
+            ->texture_sized_color_renderable_internal_format.IsValid(
+                internal_format)));
   bool depth_renderable = feature_info->validators()->
       texture_depth_renderable_internal_format.IsValid(internal_format);
   bool stencil_renderable = feature_info->validators()->