[WebGL 2] primitive restart should be always enabled

gpu/command_buffer/service/buffer_manager.cc

Index: gpu/command_buffer/service/buffer_manager.cc
diff --git a/gpu/command_buffer/service/buffer_manager.cc b/gpu/command_buffer/service/buffer_manager.cc
index 914d9b09da06e8fb3a71c2162e9a8e6291dea962..cdcd91a093e3822daa39f7c7811704a86991bbdf 100644
--- a/gpu/command_buffer/service/buffer_manager.cc
+++ b/gpu/command_buffer/service/buffer_manager.cc
@@ -34,6 +34,7 @@ BufferManager::BufferManager(MemoryTracker* memory_tracker,
       allow_buffers_on_multiple_targets_(false),
       allow_fixed_attribs_(false),
       buffer_count_(0),
+      primitive_restart_enabled_(false),
       have_context_(true),
       use_client_side_arrays_for_stream_buffers_(
           feature_info
@@ -199,13 +200,17 @@ void Buffer::ClearCache() {
 }
 
 template <typename T>
-GLuint GetMaxValue(const void* data, GLuint offset, GLsizei count) {
+GLuint GetMaxValue(const void* data, GLuint offset, GLsizei count,
+    GLuint primitive_restart_index) {
   GLuint max_value = 0;
   const T* element =
       reinterpret_cast<const T*>(static_cast<const int8_t*>(data) + offset);
   const T* end = element + count;
   for (; element < end; ++element) {
     if (*element > max_value) {
+      if (*element == primitive_restart_index) {
+        continue;
+      }
       max_value = *element;
     }
   }
@@ -217,8 +222,16 @@ bool Buffer::GetMaxValueForRange(
   Range range(offset, count, type);
   RangeToMaxValueMap::iterator it = range_set_.find(range);
   if (it != range_set_.end()) {
-    *max_value = it->second;
-    return true;
+    if (it->second.max_value_ == it->second.max_value_pr_enabled_ ||
+        (!manager_->primitive_restart_enabled_ && it->second.max_value_)) {
+      *max_value = it->second.max_value_;
+      return true;
+    }
+    if (!manager_->primitive_restart_enabled_ &&
+        it->second.max_value_pr_enabled_) {
+      *max_value = it->second.max_value_pr_enabled_;
+      return true;
+    }
   }
 
   uint32_t size;
@@ -240,30 +253,67 @@ bool Buffer::GetMaxValueForRange(
   }
 
   // Scan the range for the max value and store
+  bool index_buffer =
+      this->initial_target() == GL_ELEMENT_ARRAY_BUFFER ? true : false;
+  GLuint primitive_restart_index = 0;
+
   GLuint max_v = 0;
   switch (type) {
     case GL_UNSIGNED_BYTE:
-      max_v = GetMaxValue<uint8_t>(shadow_.get(), offset, count);
+      if (index_buffer && manager_->primitive_restart_enabled_) {
+        primitive_restart_index = 0xFF;
+      }
+      max_v = GetMaxValue<uint8_t>(shadow_.get(), offset, count,
+          primitive_restart_index);
       break;
     case GL_UNSIGNED_SHORT:
       // Check we are not accessing an odd byte for a 2 byte value.
       if ((offset & 1) != 0) {
         return false;
       }
-      max_v = GetMaxValue<uint16_t>(shadow_.get(), offset, count);
+      if (index_buffer && manager_->primitive_restart_enabled_) {
+        primitive_restart_index = 0xFFFF;
+      }
+      max_v = GetMaxValue<uint16_t>(shadow_.get(), offset, count,
+          primitive_restart_index);
       break;
     case GL_UNSIGNED_INT:
       // Check we are not accessing a non aligned address for a 4 byte value.
       if ((offset & 3) != 0) {
         return false;
       }
-      max_v = GetMaxValue<uint32_t>(shadow_.get(), offset, count);
+      if (index_buffer && manager_->primitive_restart_enabled_) {
+        primitive_restart_index = 0xFFFFFFFF;
+      }
+      max_v = GetMaxValue<uint32_t>(shadow_.get(), offset, count,
+          primitive_restart_index);
       break;
     default:
       NOTREACHED();  // should never get here by validation.
       break;
   }
-  range_set_.insert(std::make_pair(range, max_v));
+
+  if (it != range_set_.end()) {
+    if (manager_->primitive_restart_enabled_) {
+      it->second.max_value_ = max_v;
+    } else {
+      it->second.max_value_pr_enabled_ = max_v;
+    }
+  } else {
+    GLuint temp_max_value = 0, temp_max_value_pr_enabled = 0;
+    if (!index_buffer) {
+      temp_max_value = max_v;
+      temp_max_value_pr_enabled = max_v;
+    } else {
+      if (manager_->primitive_restart_enabled_) {
+        temp_max_value_pr_enabled = max_v;
+      } else {
+        temp_max_value = max_v;
+      }
+    }
+    struct MaxValue value(temp_max_value, temp_max_value_pr_enabled);
+    range_set_.insert(std::make_pair(range, value));
+  }
   *max_value = max_v;
   return true;
 }
@@ -536,6 +586,12 @@ Buffer* BufferManager::GetBufferInfoForTarget(
   }
 }
 
+void BufferManager::SetPrimitiveRestartState(bool enabled) {
+  if (primitive_restart_enabled_ != enabled) {
+    primitive_restart_enabled_ = enabled;
+  }
+}
+
 bool BufferManager::OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
                                  base::trace_event::ProcessMemoryDump* pmd) {
   const int client_id = memory_tracker_->ClientId();