Add PDF viewer example.

DEPS

Index: DEPS
diff --git a/DEPS b/DEPS
index b92a671341d2c2d6be4775c19f4f5aa773c105db..c471a1563ad35386a212012a01d7cba3661a5bb1 100644
--- a/DEPS
+++ b/DEPS
@@ -28,6 +28,7 @@ vars = {
   'libcxxabi_revision': '4ad1009ab3a59fa7a6896d74d5e4de5885697f95',
   'chromium_git': 'https://chromium.googlesource.com',
   'skia_git': 'https://skia.googlesource.com',
+  'pdfium_git': 'https://pdfium.googlesource.com',
   'boringssl_git': 'https://boringssl.googlesource.com',
   'sfntly_revision': '1bdaae8fc788a5ac8936d68bf24f37d977a13dac',
   'skia_revision': '32501a1bd4964576264795ada7e9c3bf572285b3',
@@ -45,6 +46,10 @@ vars = {
   # and whatever else without interference from each other.
   'buildtools_revision': '56bc51aff4175d3fa27dcd0faa2c345ab046c8a5',
   # Three lines of non-changing comments so that
+  # the commit queue can handle CLs rolling PDFium
+  # and whatever else without interference from each other.
+  'pdfium_revision': '767aebbef641a89498deebc29369a078207b4dcc',
+  # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling BoringSSL
   # and whatever else without interference from each other.
   'boringssl_revision': '751e889b1d791d2b91c1437248454fa1d4e101a5',
@@ -123,6 +128,9 @@ deps = {
   'src/third_party/mesa/src':
    Var('chromium_git') + '/chromium/deps/mesa.git' + '@' + '9731cb962963bca8a05f3d0f6ea40c3a781f0537',
 
+  'src/third_party/pdfium':
+   'https://pdfium.googlesource.com/pdfium.git' + '@' +  Var('pdfium_revision'),
+
   'src/third_party/boringssl/src':
    'https://boringssl.googlesource.com/boringssl.git' + '@' +  Var('boringssl_revision'),
 }