There are many species and hybrids of California-lilac (Ceanothus) available ranging from low groundcovers to small trees.
Though most forms are evergreen, there are deciduous Ceanothus, which are often the best choice for colder climates.
Flower colour ranges, from white, to pink and lavender-purple, as well as all shades of blue, for which the plants are most famous.
This genus in the Buckthorn family (Rhamnaceae) is native throughout North America and Central America, but is most diverse in the California Floristic Province, where an adaptive radiation of many species has evolved over the last few million years or so.
From the OP photo, it is not possible to definitely identify the cultivar, especially when considering the tendency for flower colour to photograph very differently depending on light conditions. Some likely candidates might include Ceanothus x 'Concha' and Ceanothus x 'Puget Blue'.