Revert of Fix ReadPixels from float fbo buffer in ES2/WebGL1.

gpu/command_buffer/common/gles2_cmd_utils.cc

Index: gpu/command_buffer/common/gles2_cmd_utils.cc
diff --git a/gpu/command_buffer/common/gles2_cmd_utils.cc b/gpu/command_buffer/common/gles2_cmd_utils.cc
index 9f3cbb2585ae53ee1bf7cecf81961bc3a11e897b..8eeaf2488c4e18d0a9248a8743b47d7159ad749e 100644
--- a/gpu/command_buffer/common/gles2_cmd_utils.cc
+++ b/gpu/command_buffer/common/gles2_cmd_utils.cc
@@ -1067,16 +1067,30 @@
     case GL_RG32F:
     case GL_RGB32F:
     case GL_RGBA32F:
-    case GL_R11F_G11F_B10F:
-      return GL_UNSIGNED_BYTE;
+      return GL_FLOAT;
     case GL_R16F:
     case GL_RG16F:
+    case GL_R11F_G11F_B10F:
     case GL_RGB16F:
     case GL_RGBA16F:
-      return GL_HALF_FLOAT;
-    default:
-      // Unsized internal format.
-      return texture_type;
+      // TODO(zmo): Consider return GL_UNSIGNED_INT_10F_11F_11F_REV and
+      // GL_HALF_FLOAT.
+      return GL_FLOAT;
+    case GL_RGBA:
+    case GL_RGB:
+      // Unsized internal format, check the type
+      switch (texture_type) {
+        case GL_FLOAT:
+        case GL_HALF_FLOAT_OES:
+          return GL_FLOAT;
+        // TODO(zmo): Consider return GL_UNSIGNED_SHORT_5_6_5,
+        // GL_UNSIGNED_SHORT_4_4_4_4, GL_UNSIGNED_SHORT_5_5_5_1, and
+        // GL_UNSIGNED_INT_2_10_10_10_REV.
+        default:
+          return GL_UNSIGNED_BYTE;
+      }
+    default:
+      return GL_UNSIGNED_BYTE;
   }
 }