Reduce per-tab memory to 128M maximum, reduce default maximum across all tabs to 256M

content/common/gpu/gpu_memory_manager.h

Index: content/common/gpu/gpu_memory_manager.h
diff --git a/content/common/gpu/gpu_memory_manager.h b/content/common/gpu/gpu_memory_manager.h
index 1023120ee2364a6f71768ca042121a112b25505f..85c0e0148f50b65e71047030d39371bba58907a2 100644
--- a/content/common/gpu/gpu_memory_manager.h
+++ b/content/common/gpu/gpu_memory_manager.h
@@ -87,6 +87,11 @@ class CONTENT_EXPORT GpuMemoryManager :
     return bytes_available_gpu_memory_;
   }
 
+  // The maximum amount of memory that a tab may be assigned
+  size_t GetMaximumTabAllocation() const {
+    return 128 * 1024 * 1024;
+  }
+
   // The minimum non-zero amount of memory that a tab may be assigned
   size_t GetMinimumTabAllocation() const {
 #if defined(OS_ANDROID)