Capture/Replay: Support multi-digit context

The code is designed for single digit contexts, i.e 1-9.
We've hit our first app that uses context 10, so update the logic.

Bug: b/184105957
Bug: angleproject:5807
Change-Id: Ice5facad8a86f009c0a85d184db4a20e48eff248
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2796402
Commit-Queue: Cody Northrop <cnorthrop@google.com>
Reviewed-by: Tim Van Patten <timvp@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>

scripts/code_generation_hashes/restricted_traces.json

@@ -50,7 +50,7 @@
   "src/tests/restricted_traces/free_fire.tar.gz.sha1":
     "a4e7aba54fb48524bb4f3022623bc7cd",
   "src/tests/restricted_traces/gen_restricted_traces.py":
-    "7df2fbfb890d54ea9932b443439ae97e",
+    "e16f270a02d11ad334cdd43bdff8b068",
   "src/tests/restricted_traces/google_maps.tar.gz.sha1":
     "5d7001969619570e80e5a39b1ab8b0c4",
   "src/tests/restricted_traces/happy_color.tar.gz.sha1":

src/tests/restricted_traces/gen_restricted_traces.py

@@ -302,10 +302,17 @@ def get_context(trace):
     for file in os.listdir(trace):
         # Load up the only header present for each trace
         if fnmatch.fnmatch(file, '*.h'):
-            # Strip the extension to isolate the context
-            context = file[len(file) - 3]
-            assert context.isdigit() == True, "Failed to find trace context number"
-            assert file[len(file) - 4].isdigit() == False, "Context number is higher than 9"
+            # Strip the extension to isolate the context by scanning
+            # for numbers leading up to the last one, i.e.:
+            #     app_capture_context123.h
+            #                          ^^
+            #                  start---||---end
+            start = len(file) - 3
+            end = start + 1
+            while file[start - 1].isdigit():
+                start -= 1
+            context = file[start:end]
+            assert context.isnumeric(), "Failed to find trace context number"
             return context