Trichrome: Assert that static_library_provider is set.

So that we don't accidentally add new targets that don't set
the variable (which is required for compile deps and wrapper scripts
to work properly).

Change-Id: I8541f2fe83bd7ced7a9d215b415c009abda37468
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2003568Reviewed-by: Richard Coles <torne@chromium.org>
Commit-Queue: Eric Stevenson <estevenson@chromium.org>
Auto-Submit: Eric Stevenson <estevenson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#734040}

android_webview/system_webview_apk_tmpl.gni

@@ -68,6 +68,10 @@ template("system_webview_apk_or_module_tmpl") {
 
     _use_trichrome_library =
         defined(use_trichrome_library) && use_trichrome_library
+    assert(
+        _use_trichrome_library == defined(invoker.static_library_provider),
+        "If trichrome library is used, static_library_provider must be set " +
+            "so that a dep can be added on the library APK.")
 
     # Pure 32-bit implies a 32-bit only Webview built on a 64-bit configuration.
     _pure_32_bit =

chrome/android/chrome_public_apk_tmpl.gni

@@ -78,6 +78,9 @@ template("chrome_public_common_apk_or_module_tmpl") {
   assert(_is_64_bit_browser || !_is_64_bit_browser)  # Mark as used.
   assert(!(_is_monochrome && _is_trichrome),
          "Cannot be both trichrome and monochrome!")
+  assert(_is_trichrome == defined(invoker.static_library_provider),
+         "If trichrome library is used, static_library_provider must be set " +
+             "so that a dep can be added on the library APK.")
 
   # Adds unwind table asset to the chrome apk for the given library target. This
   # is not part of generic apk assets target since it depends on the main shared