[android] Fix compilation SharedMemoryLimits::ForDisplayCompositor

CL [1] is moving content/renderer/media/stream/webmediaplayer_ms.cc
to Blink.
This means that gpu/command_buffer/client/shared_memory_limits.h
will get indirectly included/built as part a Blink GN target,
which has more strict compiler policies than some other modules
of Chromium.

For completeness, gpu/command_buffer/client/shared_memory_limits.h
gets pulled in indirectly by

  webmediaplayer_ms.cc ->
  services/viz/public/cpp/gpu/context_provider_command_buffer.h ->
  gpu/command_buffer/client/shared_memory_limits.h

This CL fixes a compilation triggered as part of the move above [2].

[1] https://crrev.com/c/1698170
[2] https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8908110892227907632/+/steps/compile__with_patch_/0/stdout

BUG=704136

Change-Id: I77d0716bc61fc94b314f4adc95a85624e3ee955d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1698442
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Reviewed-by: Sunny Sachanandani <sunnyps@chromium.org>
Cr-Commit-Position: refs/heads/master@{#677122}

gpu/command_buffer/client/shared_memory_limits.h

@@ -80,8 +80,8 @@ struct SharedMemoryLimits {
     DCHECK(!screen_size.IsEmpty());
 
     SharedMemoryLimits limits;
-    constexpr size_t kBytesPerPixel = 4;
-    const size_t full_screen_texture_size_in_bytes =
+    constexpr uint32_t kBytesPerPixel = 4;
+    const uint32_t full_screen_texture_size_in_bytes =
         screen_size.width() * screen_size.height() * kBytesPerPixel;
 
     // Android uses a smaller command buffer for the display compositor. Meant