Roll clang 321529:324578

This changes the Clang version number from 6.0.0 to 7.0.0.

Bug: 803661

Change-Id: Ib717cadcb3873d6dc3e49267629f7ffc1acf1df7
Reviewed-on: https://chromium-review.googlesource.com/903927
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Hans Wennborg <hans@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#535693}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: ca5066b992b8a05e6a3df042f2c0e1766e13a565

toolchain/toolchain.gni

@@ -48,12 +48,7 @@ hermetic_xcode_path =
 declare_args() {
   if (is_clang) {
     # Clang compiler version. Clang files are placed at version-dependent paths.
-    if (llvm_force_head_revision) {
-      clang_version = "7.0.0"
-    } else {
-      # TODO(hans): Trunk was updated; remove after the next roll.
-      clang_version = "6.0.0"
-    }
+    clang_version = "7.0.0"
   }
 }