Clean up some of the shader compilation code.

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 f37c61a4808d9832879583c2321d05c2fdac9602..aff07dcfe5add1161890633aae771de483c37379 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.cc
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.cc
@@ -7050,15 +7050,21 @@ GLuint GLES2DecoderImpl::DoGetMaxValueInBufferCHROMIUM(
 void GLES2DecoderImpl::DoShaderSource(
     GLuint client_id, GLsizei count, const char** data, const GLint* length) {
   std::string str;
-  for (GLsizei ii = 0; ii < count; ++ii) {
-    str.append(data[ii]);
+  if (length) {
+    for (GLsizei ii = 0; ii < count; ++ii) {
+      str.append(data[ii], length[ii]);

[vmiura, 2015/02/04 05:49:02]

I believe the spec is that if length[ii] is NULL then it should be treated as a
0 terminated string.

[vmiura, 2015/02/04 05:55:51]

Btw, is this a bug fix that should be in it's own CL?

[David Yen, 2015/02/04 19:13:33]

Done. Strictly speaking this is not a bug fix. It is just a micro optimization
because the GLES2Implementation::ShaderSource() does the correct evaluations and
always passes a correct length array. To be sure I added a unit test also, the
unit tests passes without any changes.

+    }
+  } else {
+    for (GLsizei ii = 0; ii < count; ++ii) {
+      str.append(data[ii]);
+    }
   }
   Shader* shader = GetShaderInfoNotProgram(client_id, "glShaderSource");
   if (!shader) {
     return;
   }
   // Note: We don't actually call glShaderSource here. We wait until
-  // the call to glCompileShader.
+  // we actually compile the shader.
   shader->set_source(str);
 }