Move a bunch of code in content\common (as well as a few left in renderer) to the content namespace.

ppapi/proxy/ppapi_command_buffer_proxy.cc

Index: ppapi/proxy/ppapi_command_buffer_proxy.cc
===================================================================
--- ppapi/proxy/ppapi_command_buffer_proxy.cc	(revision 163290)
+++ ppapi/proxy/ppapi_command_buffer_proxy.cc	(working copy)
@@ -76,8 +76,8 @@
 }
 
 void PpapiCommandBufferProxy::SetMemoryAllocationChangedCallback(
-      const base::Callback<void(const GpuMemoryAllocationForRenderer&)>&
-          callback) {
+    const base::Callback<void(
+      const content::GpuMemoryAllocationForRenderer&)>& callback) {
   NOTIMPLEMENTED();
 }