super hacky opaque black clear bug workaround

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 cd29b4cb87ec7ff9eda0e9947fc8609971f9a7a0..d1614cba0bd8e72c96234c1f474e78a643676e16 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -2137,7 +2137,7 @@ class GLES2DecoderImpl : public GLES2Decoder, public ErrorStateClient {
   // If the back buffer has a non-emulated alpha channel, the clear color should
   // be 0. Otherwise, the clear color should be 1.
   GLfloat BackBufferAlphaClearColor() const {
-    return offscreen_buffer_should_have_alpha_ ? 0.f : 1.f;
+    return offscreen_buffer_should_have_alpha_ ? 0.f : 1.001f;
   }
 
   // Set remaining commands to process to 0 to force DoCommands to return
@@ -2613,7 +2613,7 @@ ScopedResolvedFramebufferBinder::ScopedResolvedFramebufferBinder(
                          decoder_->offscreen_target_frame_buffer_->id());
     decoder_->state_.SetDeviceColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_TRUE);
     decoder->state_.SetDeviceCapabilityState(GL_SCISSOR_TEST, false);
-    glClearColor(0, 0, 0, 1);
+    glClearColor(0, 0, 0, 1.001);
     glClear(GL_COLOR_BUFFER_BIT);
     decoder_->RestoreClearState();
   }
@@ -3587,7 +3587,7 @@ bool GLES2DecoderImpl::Initialize(
     // alpha, clear the surface alpha to 1.0 to be correct on ReadPixels/etc.
     bool clear_alpha = back_buffer_color_format_ == GL_RGB && alpha_bits > 0;
     if (clear_alpha) {
-      glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
+      glClearColor(0.0f, 0.0f, 0.0f, 1.001f);
     }
 
     // Clear the backbuffer.
@@ -7717,7 +7717,7 @@ void GLES2DecoderImpl::RestoreClearState() {
   framebuffer_state_.clear_state_dirty = true;
   glClearColor(
       state_.color_clear_red, state_.color_clear_green, state_.color_clear_blue,
-      state_.color_clear_alpha);
+      state_.color_clear_alpha + 0.001);
   glClearStencil(state_.stencil_clear);
   glClearDepth(state_.depth_clear);
   state_.SetDeviceCapabilityState(GL_SCISSOR_TEST,
@@ -8652,7 +8652,7 @@ bool GLES2DecoderImpl::VerifyMultisampleRenderbufferIntegrity(
 
   state_.SetDeviceColorMask(
       color_mask[0], color_mask[1], color_mask[2], color_mask[3]);
-  glClearColor(clear_color[0], clear_color[1], clear_color[2], clear_color[3]);
+  glClearColor(clear_color[0], clear_color[1], clear_color[2], clear_color[3] + 0.001);
   glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER, draw_framebuffer);
   glBindFramebufferEXT(GL_READ_FRAMEBUFFER, read_framebuffer);