Add GL_EXT_color_buffer_half_float support

gpu/command_buffer/service/feature_info.h

Index: gpu/command_buffer/service/feature_info.h
diff --git a/gpu/command_buffer/service/feature_info.h b/gpu/command_buffer/service/feature_info.h
index fa0da85fdd72f796a793622f5d9e86ae5e8c2f47..a2a7f51926ada8beef75607f7ad7738f76eeea61 100644
--- a/gpu/command_buffer/service/feature_info.h
+++ b/gpu/command_buffer/service/feature_info.h
@@ -53,6 +53,7 @@ class GPU_EXPORT FeatureInfo : public base::RefCounted<FeatureInfo> {
     bool enable_texture_float_linear = false;
     bool enable_texture_half_float_linear = false;
     bool enable_color_buffer_float = false;
+    bool enable_color_buffer_half_float = false;
     bool angle_translated_shader_source = false;
     bool angle_pack_reverse_row_order = false;
     bool arb_texture_rectangle = false;
@@ -167,6 +168,7 @@ class GPU_EXPORT FeatureInfo : public base::RefCounted<FeatureInfo> {
   void EnableCHROMIUMColorBufferFloatRGBA();
   void EnableCHROMIUMColorBufferFloatRGB();
   void EnableEXTColorBufferFloat();
+  void EnableEXTColorBufferHalfFloat();
   void EnableOESTextureFloatLinear();
   void EnableOESTextureHalfFloatLinear();
 
@@ -181,12 +183,14 @@ class GPU_EXPORT FeatureInfo : public base::RefCounted<FeatureInfo> {
  private:
   friend class base::RefCounted<FeatureInfo>;
   friend class BufferManagerClientSideArraysTest;
+  class StringSet;
 
   ~FeatureInfo();
 
   void AddExtensionString(const char* s);
   void InitializeBasicState(const base::CommandLine* command_line);
   void InitializeFeatures();
+  void InitializeFloatAndHalfFloatFeatures(const StringSet& extensions);
 
   Validators validators_;