Update from https://crrev.com/312398

gpu/command_buffer/service/gles2_cmd_decoder_unittest_textures.cc

Index: gpu/command_buffer/service/gles2_cmd_decoder_unittest_textures.cc
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder_unittest_textures.cc b/gpu/command_buffer/service/gles2_cmd_decoder_unittest_textures.cc
index b0e8e8c9c703477e38d42887e01dfa45f56c67a9..f0cadf1f159ca0097aea03fad942042e996bd938 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder_unittest_textures.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder_unittest_textures.cc
@@ -1803,6 +1803,32 @@ TEST_P(GLES2DecoderTest, CopyTexSubImage2DClearsUnclearedTexture) {
   CopyTexSubImage2D cmd;
   cmd.Init(GL_TEXTURE_2D, 0, 0, 0, 0, 0, 1, 1);
   EXPECT_EQ(error::kNoError, ExecuteCmd(cmd));
+
+  TextureManager* manager = group().texture_manager();
+  TextureRef* texture_ref = manager->GetTexture(client_texture_id_);
+  ASSERT_TRUE(texture_ref != NULL);
+  Texture* texture = texture_ref->texture();
+  EXPECT_TRUE(texture->SafeToRenderFrom());
+}
+
+TEST_P(GLES2DecoderTest, CopyTexSubImage2DClearsUnclearedBackBufferSizedTexture) {
+  DoBindTexture(GL_TEXTURE_2D, client_texture_id_, kServiceTextureId);
+  DoTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, kBackBufferWidth, kBackBufferHeight,
+               0, GL_RGBA, GL_UNSIGNED_BYTE, 0, 0);
+
+  EXPECT_CALL(*gl_, CopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0,
+                                      kBackBufferWidth, kBackBufferHeight))
+      .Times(1)
+      .RetiresOnSaturation();
+  CopyTexSubImage2D cmd;
+  cmd.Init(GL_TEXTURE_2D, 0, 0, 0, 0, 0, kBackBufferWidth, kBackBufferHeight);
+  EXPECT_EQ(error::kNoError, ExecuteCmd(cmd));
+
+  TextureManager* manager = group().texture_manager();
+  TextureRef* texture_ref = manager->GetTexture(client_texture_id_);
+  ASSERT_TRUE(texture_ref != NULL);
+  Texture* texture = texture_ref->texture();
+  EXPECT_TRUE(texture->SafeToRenderFrom());
 }
 
 TEST_P(GLES2DecoderManualInitTest, CompressedImage2DMarksTextureAsCleared) {