ASSERT each linkProgram leads to empty cache in ProgramInfoManager.

The current mechanism is to clean all cache, which is very misleading.

Everytime we call LinkProgram, we simply delete the Program in the map,
getting rid of all cahces, and create a new Program.

BUG=429053
TEST=gpu_unittests
R=bajones@chromium.org

Review URL: https://codereview.chromium.org/933393003

Cr-Commit-Position: refs/heads/master@{#316937}

gpu/command_buffer/client/program_info_manager.cc

@@ -332,11 +332,10 @@ void ProgramInfoManager::Program::UpdateES2(const std::vector<int8>& result) {
   if (!link_status_) {
     return;
   }
-  attrib_infos_.clear();
-  uniform_infos_.clear();
-  frag_data_locations_.clear();
-  max_attrib_name_length_ = 0;
-  max_uniform_name_length_ = 0;
+  DCHECK_EQ(0u, attrib_infos_.size());
+  DCHECK_EQ(0u, uniform_infos_.size());
+  DCHECK_EQ(0, max_attrib_name_length_);
+  DCHECK_EQ(0, max_uniform_name_length_);
   const ProgramInput* inputs = LocalGetAs<const ProgramInput*>(
       result, sizeof(*header),
       sizeof(ProgramInput) * (header->num_attribs + header->num_uniforms));
@@ -382,8 +381,8 @@ void ProgramInfoManager::Program::UpdateES3UniformBlocks(
     // This should only happen on a lost context.
     return;
   }
-  uniform_blocks_.clear();
-  active_uniform_block_max_name_length_ = 0;
+  DCHECK_EQ(0u, uniform_blocks_.size());
+  DCHECK_EQ(0u, active_uniform_block_max_name_length_);
 
   // |result| comes from GPU process. We consider it trusted data. Therefore,
   // no need to check for overflows as the GPU side did the checks already.
@@ -453,7 +452,7 @@ void ProgramInfoManager::Program::UpdateES3Uniformsiv(
     // This should only happen on a lost context.
     return;
   }
-  uniforms_es3_.clear();
+  DCHECK_EQ(0u, uniforms_es3_.size());
 
   // |result| comes from GPU process. We consider it trusted data. Therefore,
   // no need to check for overflows as the GPU side did the checks already.
@@ -495,8 +494,8 @@ void ProgramInfoManager::Program::UpdateES3TransformFeedbackVaryings(
     // This should only happen on a lost context.
     return;
   }
-  transform_feedback_varyings_.clear();
-  transform_feedback_varying_max_length_ = 0;
+  DCHECK_EQ(0u, transform_feedback_varyings_.size());
+  DCHECK_EQ(0u, transform_feedback_varying_max_length_);
 
   // |result| comes from GPU process. We consider it trusted data. Therefore,
   // no need to check for overflows as the GPU side did the checks already.