Enforce RGB even on buggy drivers.

gpu/command_buffer/service/texture_manager.h

Index: gpu/command_buffer/service/texture_manager.h
diff --git a/gpu/command_buffer/service/texture_manager.h b/gpu/command_buffer/service/texture_manager.h
index 6b7ff12bd7846b3e1847abe4735331e871738559..2fc1cb9d381b588ca3191bfd8e905de34c8bd9a0 100644
--- a/gpu/command_buffer/service/texture_manager.h
+++ b/gpu/command_buffer/service/texture_manager.h
@@ -42,6 +42,7 @@ class TextureManager {
           cube_complete_(false),
           npot_(false),
           has_been_bound_(false),
+          framebuffer_attachment_count_(0),
           owned_(true) {
     }
 
@@ -131,6 +132,19 @@ class TextureManager {
       owned_ = false;
     }
 
+    bool IsAttachedToFramebuffer() const {
+      return framebuffer_attachment_count_ != 0;
+    }
+
+    void AttachToFramebuffer() {
+      ++framebuffer_attachment_count_;
+    }
+
+    void DetachFromFramebuffer() {
+      DCHECK(framebuffer_attachment_count_ > 0);
+      --framebuffer_attachment_count_;
+    }
+
    private:
     friend class TextureManager;
     friend class base::RefCounted<TextureInfo>;
@@ -240,6 +254,9 @@ class TextureManager {
     // Whether this texture has ever been bound.
     bool has_been_bound_;
 
+    // The number of framebuffers this texture is attached to.
+    int framebuffer_attachment_count_;
+
     // Whether the associated context group owns this texture and should delete
     // it.
     bool owned_;