[Reland] Fix ReadPixels from float fbo buffer in ES2/WebGL1.

gpu/command_buffer/tests/gl_readback_unittest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>
 #include <GLES2/gl2extchromium.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 123 matching lines @@
   GLint compile_status = 0;
   glGetShaderiv(shader, GL_COMPILE_STATUS, &compile_status);
   if (compile_status != GL_TRUE) {
     glDeleteShader(shader);
     shader = 0;
   }
 
   return shader;
 }
 
-TEST_F(GLReadbackTest, ReadPixelsFloat) {
+// TODO(zmo): ReadPixels with float type isn't implemented in ANGLE ES2
+// backend. crbug.com/607283.
+// TODO(zmo): This test also fails on some android devices when the readback
+// type is HALF_FLOAT_OES. Likely it's due to a driver bug. crbug.com/607936.

[Zhenyao Mo, 2016/04/29 18:16:48]

This is the added part from the original CL: in this CL, we also disable the
test on ANDROID.

+#if defined(OS_WIN) || defined(OS_ANDROID)
+#define MAYBE_ReadPixelsFloat DISABLED_ReadPixelsFloat
+#else
+#define MAYBE_ReadPixelsFloat ReadPixelsFloat
+#endif
+TEST_F(GLReadbackTest, MAYBE_ReadPixelsFloat) {
   const GLsizei kTextureSize = 4;
   const GLfloat kDrawColor[4] = { -10.9f, 0.5f, 10.5f, 100.12f };
   const GLfloat kEpsilon = 0.01f;
 
   struct TestFormat {
     GLint format;
     GLint type;
     uint32_t comp_count;
   };
   TestFormat test_formats[4];
@@ skipping 158 matching lines @@
 
     glDeleteFramebuffers(1, &framebuffer);
     glDeleteTextures(1, &texture_id);
   }
 
   glDeleteBuffers(1, &vertex_buffer);
   glDeleteProgram(program);
 }
 
 }  // namespace gpu