Hook ANGLE_request_extension up to the passthrough cmd decoder.

third_party/WebKit/Source/modules/webgl/WebGLDrawBuffers.cpp

Index: third_party/WebKit/Source/modules/webgl/WebGLDrawBuffers.cpp
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLDrawBuffers.cpp b/third_party/WebKit/Source/modules/webgl/WebGLDrawBuffers.cpp
index dd5047330e1f78625ce29b75a3d7a95f2df2d702..6d024272b66e814464ce57ccf80b00234a9e7826 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLDrawBuffers.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGLDrawBuffers.cpp
@@ -102,6 +102,12 @@ bool WebGLDrawBuffers::satisfiesWebGLRequirements(
   gpu::gles2::GLES2Interface* gl = webglContext->contextGL();
   Extensions3DUtil* extensionsUtil = webglContext->extensionsUtil();
 
+  if (extensionsUtil->isExtensionRequestable("GL_EXT_draw_buffers")) {

[Zhenyao Mo, 2017/02/15 23:24:20]

This is also true even if the extension is not enabled, i.e., the code after
this block will never be hit.

I am OK with deleting this satisfiesWebGLRequirements() and trust the drivers to
do the right thing. (If someone reports a bad driver, then let's add a
workaround to disable this extension inside command buffer).

[Geoff Lang, 2017/02/16 15:38:45]

Removed this method.  I agree and prefer to trust the driver until we find
issues.

+    // Extension can be enabled but is not yet so we trust that the command
+    // decoder has full support
+    return true;
+  }
+
   // This is called after we make sure GL_EXT_draw_buffers is supported.
   GLint maxDrawBuffers = 0;
   GLint maxColorAttachments = 0;