SuperSize: Hardcode path for ndk objdump in Disassemble()

Allows Disassemble() to work for arm32 builds when output directory is
not set.

Bug: 999351
Change-Id: I6da45eb0c945f0239bd455b421ed0589ee987e2d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2606515Reviewed-by: Matthew Denton <mpdenton@chromium.org>
Commit-Queue: Matthew Denton <mpdenton@chromium.org>
Auto-Submit: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#839694}

tools/binary_size/libsupersize/console.py

@@ -340,6 +340,19 @@ class _Session(object):
       tool_prefix = path_util.ToolPrefixFinder(
           output_directory=output_directory_finder.Finalized(),
           linker_name='ld').Finalized()
+    else:
+      # Output directory is not set, so we cannot load tool_prefix from
+      # build_vars.json, nor resolve the output directory-relative path stored
+      # size_info.metadata.
+      is_android = next(
+          filter(None, (m.get(models.METADATA_APK_FILENAME)
+                        for m in size_info.metadata)), None)
+      arch = next(
+          filter(None, (m.get(models.METADATA_ELF_ARCHITECTURE)
+                        for m in size_info.metadata)), None)
+      # Hardcode path for arm32.
+      if is_android and arch == 'arm':
+        tool_prefix = path_util.ANDROID_ARM_NDK_TOOL_PREFIX
 
     args = [
         path_util.GetObjDumpPath(tool_prefix),

tools/binary_size/libsupersize/path_util.py

@@ -23,6 +23,11 @@ TOOLS_SRC_ROOT = os.environ.get(
 
 _SAMPLE_TOOL_SUFFIX = 'readelf'
 
+ANDROID_ARM_NDK_TOOL_PREFIX = os.path.join(TOOLS_SRC_ROOT, 'third_party',
+                                           'android_ndk', 'toolchains', 'llvm',
+                                           'prebuilt', 'linux-x86_64', 'bin',
+                                           'arm-linux-androideabi-')
+
 
 class _PathFinder(object):
   def __init__(self, name, value):