Add a basic linux client for Blimp.

blimp/client/BUILD.gn

Index: blimp/client/BUILD.gn
diff --git a/blimp/client/BUILD.gn b/blimp/client/BUILD.gn
index 3858bd3e9ee035a82a175afd2b13eb89f341007b..b6abccccbdc2fb8e978d3ae93a04be19326193f1 100644
--- a/blimp/client/BUILD.gn
+++ b/blimp/client/BUILD.gn
@@ -10,6 +10,8 @@ if (is_android) {
 component("blimp_client") {
   sources = [
     "blimp_client_export.h",
+    "blimp_startup.cc",
+    "blimp_startup.h",
     "compositor/blimp_compositor.cc",
     "compositor/blimp_compositor.h",
     "compositor/blimp_context_provider.cc",
@@ -83,6 +85,30 @@ source_set("unit_tests") {
   ]
 }
 
+if (is_linux) {
+  executable("blimp_shell") {

[haibinlu, 2015/12/17 00:32:58]

blimp_client_shell?

[nyquist, 2015/12/17 03:00:21]

Good question. I guess currently it follows 'content_shell'. Then again,
//content isn't split between client and engine.

Will we ever have a blimp_engine_shell though?

I don't feel strongly. Either way is fine with me.

[Wez, 2016/01/05 19:15:01]

No, the client+engine are equivalent to content_shell, in effect - it'd be
reasonable to call this blimp_shell, but probably more understandable to call it
simply blimp_client.

+    sources = [
+      "linux/blimp_display_manager.cc",
+      "linux/blimp_display_manager.h",
+      "linux/blimp_main.cc",
+      "session/blimp_client_session_linux.cc",
+      "session/blimp_client_session_linux.h",
+    ]
+
+    deps = [
+      ":blimp_client",
+      "//base",
+      "//ui/events/platform/x11",
+      "//ui/platform_window/x11",
+    ]
+
+    public_configs = [ "//build/config/linux:x11" ]
+    public_deps = [
+      "//ui/events/platform/x11",

[nyquist, 2015/12/17 03:00:21]

Optional nit: Could this follow the same style as the previous line?

[Wez, 2016/01/05 19:15:01]

I think we can just run the gn formatter over this file to get the preferred
style?

+    ]
+  }
+}
+
 if (is_android) {
   manifest_package = "org.chromium.blimp"
   blimp_apk_manifest = "$target_gen_dir/blimp_apk_manifest/AndroidManifest.xml"