Add EXT_color_buffer_half_float extension support in GPU commandbuffer service.

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 70837bf1f9d083b092e9a0bd5bdb745561c2304c..8905210b9668880f6d391b86abcbf46d0cc8a88e 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -6808,6 +6808,14 @@ void GLES2DecoderImpl::FinishReadPixels(
 }
 
 
+static inline GLenum GetTexType(GLenum type) {
+  if (gfx::GetGLImplementation() != gfx::kGLImplementationEGLGLES2) {
+    if (type == GL_HALF_FLOAT_OES)
+      return GL_HALF_FLOAT_ARB;
+  }
+  return type;
+}
+
 error::Error GLES2DecoderImpl::HandleReadPixels(
     uint32 immediate_data_size, const cmds::ReadPixels& c) {
   if (ShouldDeferReads())
@@ -6913,7 +6921,8 @@ error::Error GLES2DecoderImpl::HandleReadPixels(
       // If the row is in range, copy it.
       if (ry >= 0 && ry < max_size.height() && read_width > 0) {
         glReadPixels(
-            read_x, ry, read_width, 1, format, type, dst + dest_row_offset);
+            read_x, ry, read_width, 1, format, GetTexType(type),
+            dst + dest_row_offset);
       }
       dst += padded_row_size;
     }
@@ -6925,7 +6934,7 @@ error::Error GLES2DecoderImpl::HandleReadPixels(
       glBufferData(GL_PIXEL_PACK_BUFFER_ARB, pixels_size, NULL, GL_STREAM_READ);
       GLenum error = glGetError();
       if (error == GL_NO_ERROR) {
-        glReadPixels(x, y, width, height, format, type, 0);
+        glReadPixels(x, y, width, height, format, GetTexType(type), 0);
         pending_readpixel_fences_.push(linked_ptr<FenceCallback>(
             new FenceCallback()));
         WaitForReadPixels(base::Bind(
@@ -6937,7 +6946,7 @@ error::Error GLES2DecoderImpl::HandleReadPixels(
         return error::kNoError;
       }
     }
-    glReadPixels(x, y, width, height, format, type, pixels);
+    glReadPixels(x, y, width, height, format, GetTexType(type), pixels);
   }
   GLenum error = LOCAL_PEEK_GL_ERROR("glReadPixels");
   if (error == GL_NO_ERROR) {