Update GL_IMPLEMENTATION_COLOR_READ_FORMAT for BGRA

content/common/gpu/client/gl_helper_readback_support.cc

Index: content/common/gpu/client/gl_helper_readback_support.cc
diff --git a/content/common/gpu/client/gl_helper_readback_support.cc b/content/common/gpu/client/gl_helper_readback_support.cc
index e773ca90782a6dc684bec38c7afb455e1cfe925c..91df07cb342cc8214c0777f91c59efe675407f3b 100644
--- a/content/common/gpu/client/gl_helper_readback_support.cc
+++ b/content/common/gpu/client/gl_helper_readback_support.cc
@@ -104,17 +104,6 @@ bool GLHelperReadbackSupport::SupportsFormat(GLenum format, GLenum type) {
   if (format == GL_RGBA && type == GL_UNSIGNED_BYTE)
     return true;
 
-  if (format == GL_BGRA_EXT && type == GL_UNSIGNED_BYTE) {

[ericrk, 2016/03/02 17:40:30]

The presence of GL_EXT_read_format_bgra doesn't guarantee that BGRA readback is
supported, it just indicates that it may be returned from
GL_IMPLEMENTATION_COLOR_READ_FORMAT. We should always be calling that function
in all cases.

We used to avoid doing so to work around an issue where the driver would never
report BGRA from GL_IMPLEMENTATION_COLOR_READ_FORMAT, but that issue is resolved
with this CL.

-    const GLubyte* tmp = gl_->GetString(GL_EXTENSIONS);
-    if (tmp) {
-      std::string extensions =
-          " " + std::string(reinterpret_cast<const char*>(tmp)) + " ";
-      if (extensions.find(" GL_EXT_read_format_bgra ") != std::string::npos) {
-        return true;
-      }
-    }
-  }
-
   bool supports_format = false;
   GLenum ext_format = 0, ext_type = 0;
   GetAdditionalFormat(format, type, &ext_format, &ext_type);