Wrap all preprocessor code in the angle namespace.

BUG=836820
BUG=801364

Change-Id: I08b6a2f9f12b689e09df6efd916c313e71e8a051
Reviewed-on: https://chromium-review.googlesource.com/1028581
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
diff --git a/src/compiler/preprocessor/DirectiveHandlerBase.h b/src/compiler/preprocessor/DirectiveHandlerBase.h
index 6c81d01..858bc1d 100644
--- a/src/compiler/preprocessor/DirectiveHandlerBase.h
+++ b/src/compiler/preprocessor/DirectiveHandlerBase.h
@@ -9,6 +9,9 @@
 
 #include <string>
 
+namespace angle
+{
+
 namespace pp
 {
 
@@ -40,4 +43,6 @@
 
 }  // namespace pp
 
+}  // namespace angle
+
 #endif  // COMPILER_PREPROCESSOR_DIRECTIVEHANDLERBASE_H_