Work around NVIDIA driver issue with glLineWidth(NaN)

gpu/command_buffer/build_gles2_cmd_buffer.py

Index: gpu/command_buffer/build_gles2_cmd_buffer.py
diff --git a/gpu/command_buffer/build_gles2_cmd_buffer.py b/gpu/command_buffer/build_gles2_cmd_buffer.py
index 1216a7f45ae9e4c6f4f4034afa4eeb2e9583f050..aaae2724be098cf1aa2d6c3354b0145a1a380e01 100755
--- a/gpu/command_buffer/build_gles2_cmd_buffer.py
+++ b/gpu/command_buffer/build_gles2_cmd_buffer.py
@@ -425,6 +425,11 @@ _STATES = {
         'type': 'GLfloat',
         'default': '1.0f',
         'range_checks': [{'check': "<= 0.0f", 'test_value': "0.0f"}],
+        # This works around an NVIDIA driver bug, where an INVALID_VALUE error
+        # is generated if line width is set to NaN. The consequences of setting
+        # line width to NaN are undefined, so we just set it to an arbitrary
+        # valid value.
+        'convert_nan': '1.0f',
       }],
   },
   'DepthMask': {
@@ -3350,6 +3355,11 @@ class StateSetHandler(TypeHandler):
         if item.get('cached', False):
           file.Write("    state_.%s = %s;\n" %
                      (CachedStateName(item), args[ndx].name))
+      if 'convert_nan' in item:
+        file.Write('    if (base::IsNaN(%s)) {' % args[ndx].name)
+        file.Write('      %s = %s;' % (args[ndx].name, item['convert_nan']))
+        file.Write('    }\n')
+
       file.Write("    %s(%s);\n" %
                  (func.GetGLFunctionName(), func.MakeOriginalArgString("")))
     file.Write("  }\n")
@@ -7612,8 +7622,18 @@ void ContextState::InitState(const ContextState *prev_state) const {
               file.Write("(%s != prev_state->%s)" %
                          (item_name, item_name))
           if test_prev:
-            file.Write("    )\n")
+            file.Write("    ) {\n")
+          for place, item in enumerate(state['states']):
+            if 'convert_nan' in item:
+              item_name = CachedStateName(item)
+              args[place] = 'sanitized_%s' % item_name
+              file.Write('  %s %s = %s;' %
+                  (item['type'], args[place], item_name))
+              file.Write('  if (base::IsNaN(%s))' % item_name)
+              file.Write('    %s = %s;' % (args[place], item['convert_nan']))
           file.Write("  gl%s(%s);\n" % (state['func'], ", ".join(args)))
+          if test_prev:
+            file.Write("    }\n")
 
     file.Write("  if (prev_state) {")
     WriteStates(True)