Use Stub CDM for building libwidevinecdmadapter.so

third_party/widevine/cdm/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/features.gni")
 import("//chrome/process_version_rc_template.gni")
 import("//media/cdm/ppapi/cdm_paths.gni")
 import("//media/cdm/ppapi/ppapi_cdm_adapter.gni")
 import("//ppapi/features/features.gni")
 import("//third_party/widevine/cdm/widevine.gni")
 
 widevine_arch = current_cpu
 if (widevine_arch == "x86") {
   widevine_arch = "ia32"
 }
 
 widevine_cdm_binary_files = []
 widevine_cdm_manifest_file = []
 
+# Due to crbug.com/707488, in linux and chromeos chrome, we temporarily use
+# stub cdm for building cdm adapter and copy the real cdm after that.
+# The stub libwidevinecdm.so is in the sub-directory "./stub_cdm" to avoid
+# GN's complaint about generating the same output in two targets.
+# TODO(hmchen): Revert this change after crbug.com/707488 fixed.
+use_stub_cdm_for_chrome = false
+if (is_chrome_branded && (is_linux || is_chromeos)) {
+  enable_widevine = true

[xhwang, 2017/04/04 06:48:52]

This will enable VerifyCdmHost on linux and chromeos, which is not desired for
now:

https://cs.chromium.org/chromium/src/ppapi/features/features.gni?rcl=976a6d56...

It seems to me we don't really need "enable_widevine" now. All the changes are
confined with this file, and we check use_stub_cdm_for_chrome for everything.
Can you simply drop it?

[Haoming Chen, 2017/04/04 17:16:15]

Done.

+  use_stub_cdm_for_chrome = true
+}
+
 if (is_android) {
   # Always available on Android regardless of branding.
   widevine_cdm_version_h_file = "android/widevine_cdm_version.h"
 } else if (is_chrome_branded) {
   if (is_chromeos) {
     widevine_cdm_version_h_file =
         "chromeos/$widevine_arch/widevine_cdm_version.h"
     widevine_cdm_binary_files = [ "chromeos/$widevine_arch/libwidevinecdm.so" ]
   } else if (is_linux) {
     widevine_cdm_version_h_file = "linux/$widevine_arch/widevine_cdm_version.h"
@@ skipping 44 matching lines @@
     "widevine_cdm_common.h",
   ]
 
   public_deps = [
     ":version_h",  # Forward permission to use version header.
     "//media:media_features",
     "//ppapi/features",
   ]
 }
 
-if (widevine_cdm_binary_files != []) {
+if (use_stub_cdm_for_chrome) {
+  widevine_cdm_binary_files = []
+  copy("copy_widevinecdm") {
+    if (is_linux) {
+      widevine_cdm = [ "linux/$widevine_arch/libwidevinecdm.so" ]
+    } else if (is_chromeos) {
+      widevine_cdm = [ "chromeos/$widevine_arch/libwidevinecdm.so" ]
+    }
+    sources = widevine_cdm
+    outputs = [
+      "$root_out_dir/$widevine_cdm_path/{{source_file_part}}",
+    ]
+  }
+
+  shared_library("widevinecdm") {
+    output_dir = "$root_out_dir/$widevine_cdm_path/stub_cdm"
+    sources = [
+      "//media/cdm/stub/stub_cdm.cc",
+      "//media/cdm/stub/stub_cdm.h",
+    ]
+
+    defines = [ "CDM_IMPLEMENTATION" ]
+
+    deps = [
+      ":version_h",
+      ":copy_widevinecdm",
+      "//base",
+      "//build/config/sanitizers:deps",
+    ]
+
+    public_deps = [ ":copy_widevinecdm" ]
+    cflags = [ "-fvisibility=hidden" ]
+  }
+} else if (widevine_cdm_binary_files != []) {
   copy("widevinecdm") {
     sources = widevine_cdm_binary_files
     outputs = [
       "$root_out_dir/$widevine_cdm_path/{{source_file_part}}",
     ]
 
     # TODO(jrummell)
     # 'COPY_PHASE_STRIP': 'NO',
   }
 } else if (enable_widevine && enable_pepper_cdms) {
@@ skipping 62 matching lines @@
     deps = [
       ":version_h",
       ":widevinecdm",
       ":widevinecdmadapter_resources",
     ]
     data_deps = [
       ":widevine_cdm_manifest",
       ":widevinecdm",
     ]
 
-    if (is_linux) {
+    if (use_stub_cdm_for_chrome && is_linux) {
+      ldflags =
+          [ rebase_path(
+              "$root_out_dir/$widevine_cdm_path/stub_cdm/libwidevinecdm.so",
+              root_build_dir) ]

[xhwang, 2017/04/04 07:00:10]

Actually, this is not necessary since we are depending on :widevinecdm which is
a shared library. We only need this ldflag when we are copying the cdm.

[Haoming Chen, 2017/04/04 17:16:15]

Done.

+    } else if (is_linux) {
       ldflags =
           [ rebase_path("$root_out_dir/$widevine_cdm_path/libwidevinecdm.so",
                         root_build_dir) ]
     } else if (is_win) {
       ldflags =
           [ rebase_path("$root_out_dir/$widevine_cdm_path/widevinecdm.dll.lib",
                         root_build_dir) ]
     } else if (is_mac) {
       ldflags =
           [ rebase_path("$root_out_dir/$widevine_cdm_path/libwidevinecdm.dylib",
@@ skipping 25 matching lines @@
       "../scripts/signer.py",
     ]
     outputs = [
       "$root_out_dir/installer/widevine/{{source_file_part}}",
     ]
   }
 } else {
   group("widevine_signature_scripts") {
   }
 }