Cache GL's viewport on the GPU command buffer client side.

gpu/command_buffer/service/gl_utils.cc

Index: gpu/command_buffer/service/gl_utils.cc
diff --git a/gpu/command_buffer/service/gl_utils.cc b/gpu/command_buffer/service/gl_utils.cc
index a89a5fa547643d9e789ebbca2f06f94d57d2fb0a..19683c3fbe6f91107107d966921d5e0f71868d9b 100644
--- a/gpu/command_buffer/service/gl_utils.cc
+++ b/gpu/command_buffer/service/gl_utils.cc
@@ -174,6 +174,12 @@ void PopulateNumericCapabilities(Capabilities* caps,
                 &caps->max_vertex_texture_image_units);
   glGetIntegerv(GL_MAX_VERTEX_UNIFORM_VECTORS,
                 &caps->max_vertex_uniform_vectors);
+  {
+    GLint dims[2] = {0, 0};
+    glGetIntegerv(GL_MAX_VIEWPORT_DIMS, dims);
+    caps->max_viewport_width = dims[0];
+    caps->max_viewport_height = dims[1];
+  }
   glGetIntegerv(GL_NUM_COMPRESSED_TEXTURE_FORMATS,
                 &caps->num_compressed_texture_formats);
   glGetIntegerv(GL_NUM_SHADER_BINARY_FORMATS, &caps->num_shader_binary_formats);