Create correct GLES3 context for GLES3 unittest

gpu/command_buffer/service/test_helper.cc

Index: gpu/command_buffer/service/test_helper.cc
diff --git a/gpu/command_buffer/service/test_helper.cc b/gpu/command_buffer/service/test_helper.cc
index 89224142d9d653ecc0d4fe50762c2d901dfeab8a..cf79e40e65bed32e884a342a8cb908666224fe9c 100644
--- a/gpu/command_buffer/service/test_helper.cc
+++ b/gpu/command_buffer/service/test_helper.cc
@@ -575,6 +575,7 @@ void TestHelper::SetupFeatureInfoInitExpectationsWithGLVersion(
     EXPECT_CALL(*gl, CheckFramebufferStatusEXT(GL_FRAMEBUFFER))
         .WillOnce(Return(GL_FRAMEBUFFER_COMPLETE))
         .RetiresOnSaturation();
+    GLenum status_rgba = GL_FRAMEBUFFER_COMPLETE;

[qiankun, 2016/10/21 10:51:04]

See the actual executed code here:
https://cs.chromium.org/chromium/src/gpu/command_buffer/service/feature_info....

     EXPECT_CALL(*gl, TexImage2D(GL_TEXTURE_2D, 0, GL_RGB32F, width, width, 0,
         GL_RGB, GL_FLOAT, _))
         .Times(1)
@@ -587,7 +588,9 @@ void TestHelper::SetupFeatureInfoInitExpectationsWithGLVersion(
       EXPECT_CALL(*gl, CheckFramebufferStatusEXT(GL_FRAMEBUFFER))
           .WillOnce(Return(GL_FRAMEBUFFER_COMPLETE))
           .RetiresOnSaturation();
+    }
 
+    if (status_rgba == GL_FRAMEBUFFER_COMPLETE) {

[Zhenyao Mo, 2016/10/21 17:51:20]

I don't think I understand the motivation of this change.  We don't have code
path to modify |status_rgba| so this is always true. Then why do we need this?

[qiankun, 2016/10/22 11:47:13]

Yes, this always is true. I used it to align with the actual executed code, here
https://cs.chromium.org/chromium/src/gpu/command_buffer/service/feature_info.....

But previous code is wrong here because the following code is only executed when
gl_info.is_es3 == false (it's in the else branch of if statement at line 583).

[Zhenyao Mo, 2016/10/25 22:41:14]

I see. It's fine then.

       if (enable_es3 && gl_info.is_es3_capable) {
         EXPECT_CALL(*gl, TexImage2D(GL_TEXTURE_2D, 0, GL_R16F, width, width,
             0, GL_RED, GL_FLOAT, _))