Add command buffer support for EXT_sRGB_write_control

gpu/command_buffer/service/gles2_cmd_decoder.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.cc b/gpu/command_buffer/service/gles2_cmd_decoder.cc
index 3c0f126881452c0bd00de777adffe0901a3d2aa6..e8df82b84e455f46f6448c1187a15a9cf3c04e50 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -707,6 +707,7 @@ class GLES2DecoderImpl : public GLES2Decoder, public ErrorStateClient {
   // Workarounds
   void OnFboChanged() const;
   void OnUseFramebuffer() const;
+  void UpdateFramebufferSRGB(Framebuffer* framebuffer);
 
   error::ContextLostReason GetContextLostReasonFromResetStatus(
       GLenum reset_status) const;
@@ -3458,6 +3459,7 @@ bool GLES2DecoderImpl::Initialize(
   DoBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
   DoBindFramebuffer(GL_FRAMEBUFFER, 0);
   DoBindRenderbuffer(GL_RENDERBUFFER, 0);
+  UpdateFramebufferSRGB(nullptr);
 
   bool call_gl_clear = !surfaceless_ && !offscreen;
 #if defined(OS_ANDROID)
@@ -4293,21 +4295,37 @@ bool GLES2DecoderImpl::CheckBoundDrawFramebufferValid(const char* func_name) {
   Framebuffer* framebuffer = GetFramebufferInfoForTarget(target);
   bool valid = CheckFramebufferValid(
       framebuffer, target, GL_INVALID_FRAMEBUFFER_OPERATION, func_name);
-  if (valid && !features().chromium_framebuffer_multisample)
+  if (!valid)
+    return false;
+
+  if (!features().chromium_framebuffer_multisample)
     OnUseFramebuffer();
-  if (valid && feature_info_->feature_flags().desktop_srgb_support) {
-    // If framebuffer contains sRGB images, then enable FRAMEBUFFER_SRGB.
-    // Otherwise, disable FRAMEBUFFER_SRGB. Assume default fbo does not have
-    // sRGB image.
-    // In theory, we can just leave FRAMEBUFFER_SRGB on. However, many drivers
-    // behave incorrectly when all images are linear encoding, they still apply
-    // the sRGB conversion, but when at least one image is sRGB, then they
-    // behave correctly.
-    bool enable_framebuffer_srgb =
-        framebuffer && framebuffer->HasSRGBAttachments();
+
+  UpdateFramebufferSRGB(framebuffer);
+  return true;
+}
+
+void GLES2DecoderImpl::UpdateFramebufferSRGB(Framebuffer* framebuffer) {
+  // Manually set the value of FRAMEBUFFER_SRGB based on the state that was set
+  // by the client.
+  bool needs_enable_disable_framebuffer_srgb = false;
+  bool enable_framebuffer_srgb = true;
+  if (feature_info_->feature_flags().ext_srgb_write_control) {
+    needs_enable_disable_framebuffer_srgb = true;
+    enable_framebuffer_srgb &= state_.GetEnabled(GL_FRAMEBUFFER_SRGB);
+  }
+  // On desktop, enable FRAMEBUFFER_SRGB only if the framebuffer contains sRGB
+  // attachments. In theory, we can just leave FRAMEBUFFER_SRGB enabled,
+  // however,
+  // many drivers behave incorrectly when no attachments are sRGB. When at
+  // least one attachment is sRGB, then they behave correctly.
+  if (feature_info_->feature_flags().desktop_srgb_support) {
+    needs_enable_disable_framebuffer_srgb = true;

[Zhenyao Mo, 2016/11/30 19:31:11]

You can DCHECK this because desktop_srgb_support should set
ext_srgb_write_control to true.

[ccameron, 2016/11/30 23:59:44]

Done.

[ccameron, 2016/12/01 02:14:34]

Oops, now that I'm not enabling write control for WebGL contexts, this can't be
a DCHECK anymore.

+    // Assume that the default fbo does not have an sRGB image.
+    enable_framebuffer_srgb &= framebuffer && framebuffer->HasSRGBAttachments();
+  }
+  if (needs_enable_disable_framebuffer_srgb)
     state_.EnableDisableFramebufferSRGB(enable_framebuffer_srgb);
-  }
-  return valid;
 }
 
 bool GLES2DecoderImpl::CheckBoundReadFramebufferValid(
@@ -7417,6 +7435,11 @@ void GLES2DecoderImpl::DoDisable(GLenum cap) {
       // DrawElements* for old desktop GL.
       return;
     }
+    if (cap == GL_FRAMEBUFFER_SRGB) {
+      // Enable and Disable GL_FRAMEBUFFER_SRGB is done manually in
+      // CheckBoundDrawFramebufferValid.
+      return;
+    }
     glDisable(cap);
   }
 }
@@ -7429,6 +7452,11 @@ void GLES2DecoderImpl::DoEnable(GLenum cap) {
       // DrawElements* for old desktop GL.
       return;
     }
+    if (cap == GL_FRAMEBUFFER_SRGB) {
+      // Enable and Disable GL_FRAMEBUFFER_SRGB is done manually in
+      // CheckBoundDrawFramebufferValid.
+      return;
+    }
     glEnable(cap);
   }
 }