Update GPU memory buffers to use StrideInBytes internally.

content/common/gpu/client/gpu_memory_buffer_impl.cc

Index: content/common/gpu/client/gpu_memory_buffer_impl.cc
diff --git a/content/common/gpu/client/gpu_memory_buffer_impl.cc b/content/common/gpu/client/gpu_memory_buffer_impl.cc
index d3c08bdb1a09b0d1256c297148cd190d2fae5690..4b05bbff2aa1c4ce67da55713b3d020a4a9d8f0a 100644
--- a/content/common/gpu/client/gpu_memory_buffer_impl.cc
+++ b/content/common/gpu/client/gpu_memory_buffer_impl.cc
@@ -5,6 +5,7 @@
 #include "content/common/gpu/client/gpu_memory_buffer_impl.h"
 
 #include "base/logging.h"
+#include "base/numerics/safe_math.h"
 #include "content/common/gpu/client/gpu_memory_buffer_impl_shared_memory.h"
 #include "ui/gl/gl_bindings.h"
 
@@ -76,16 +77,24 @@ GpuMemoryBufferImpl* GpuMemoryBufferImpl::FromClientBuffer(
 }
 
 // static
-size_t GpuMemoryBufferImpl::BytesPerPixel(Format format) {
+bool GpuMemoryBufferImpl::StrideInBytes(size_t width,
+                                        Format format,
+                                        size_t* stride_in_bytes) {
+  base::CheckedNumeric<size_t> s = width;
   switch (format) {
     case RGBA_8888:
     case RGBX_8888:
     case BGRA_8888:
-      return 4;
+      s *= 4;
+      if (!s.IsValid())
+        return false;
+
+      *stride_in_bytes = s.ValueOrDie();
+      return true;
   }
 
   NOTREACHED();
-  return 0;
+  return false;
 }
 
 gfx::GpuMemoryBuffer::Format GpuMemoryBufferImpl::GetFormat() const {