Add Widevine plugin to binary distribution (issue #2009)

Mac: Check in widevinecdmadapter.plugin binary until Widevine GN
build errors are resolved (https://crbug.com/626436).

tools/distrib/linux/README.redistrib.txt

@@ -56,3 +56,8 @@ run but any related functionality may become broken or disabled.
   * devtools_resources.pak
     This file contains non-localized resources required for Chrome Developer
     Tools. Without this file Chrome Developer Tools will not function.
+
+* Widevine CDM support.
+  * libwidevinecdmadapter.so
+    Without this file playback of Widevine projected content will not function.
+    See the CefRegisterWidevineCdm() function in cef_web_plugin.h for usage.

tools/distrib/mac/README.redistrib.txt

@@ -103,3 +103,8 @@ run but any related functionality may become broken or disabled.
   * Chromium Embedded Framework.framework/Resources/crash_report_sender
   * Chromium Embedded Framework.framework/Resources/Info.plist
     Without these files breakpad support (crash reporting) will not function.
+
+* Widevine CDM support.
+  * widevinecdmadapter.plugin
+    Without this file playback of Widevine projected content will not function.
+    See the CefRegisterWidevineCdm() function in cef_web_plugin.h for usage.

tools/distrib/win/README.redistrib.txt

@@ -62,3 +62,8 @@ run but any related functionality may become broken or disabled.
   * libGLESv2.dll
   Without these files HTML5 accelerated content like 2D canvas, 3D CSS and WebGL
   will not function.
+
+* Widevine CDM support.
+  * widevinecdmadapter.dll
+    Without this file playback of Widevine projected content will not function.
+    See the CefRegisterWidevineCdm() function in cef_web_plugin.h for usage.

tools/make_distrib.py

@@ -650,6 +650,7 @@ elif platform == 'macosx':
       make_dir(dst_dir, options.quiet)
       copy_dir(os.path.join(build_dir, 'cefclient.app/Contents/Frameworks/%s.framework' % framework_name), \
                os.path.join(dst_dir, '%s.framework' % framework_name), options.quiet)
+      copy_file(os.path.join(script_dir, 'distrib/mac/widevinecdmadapter.plugin'), dst_dir, options.quiet)
 
       if not options.nosymbols and use_gn:
         # create the symbol output directory
@@ -670,6 +671,7 @@ elif platform == 'macosx':
     if mode != 'client':
       copy_dir(os.path.join(build_dir, 'cefclient.app/Contents/Frameworks/%s.framework' % framework_name), \
                os.path.join(dst_dir, '%s.framework' % framework_name), options.quiet)
+      copy_file(os.path.join(script_dir, 'distrib/mac/widevinecdmadapter.plugin'), dst_dir, options.quiet)
     else:
       copy_dir(os.path.join(build_dir, 'cefclient.app'), os.path.join(dst_dir, 'cefclient.app'), options.quiet)