Clean up dependencies for disk_cache histogram_macros.h.

The current mechanism by which these convenience macros find their
backend is confusing, at best; the macro has the form of our include
guard macros, but describes a CC file. Embedded within the
histogram_macros.h then is an abstraction violation: it just knows
which object has backend information depending on which file it was
included from.

Some downstream reviews have made this even more confusing; rather
than continue this, let's parameterize the backend object to the
convenience macros, so each translation unit is responsible for
knowing its own context.

R=mmenke@chromium.org, rvargas@chromium.org
TBR=mmenke@chromium.org
BUG=None

Review URL: https://codereview.chromium.org/140893013

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251116 0039d316-1c4b-4281-b951-d872f2087c98

13 files changed, 37 insertions, 25 deletions

diff --git a/net/disk_cache/backend_impl.cc b/net/disk_cache/backend_impl.cc
index d10a19d..c934b87 100644
--- a/net/disk_cache/backend_impl.cc
+++ b/net/disk_cache/backend_impl.cc
@@ -27,11 +27,11 @@
 #include "net/disk_cache/errors.h"
 #include "net/disk_cache/experiments.h"
 #include "net/disk_cache/file.h"
-
-// This has to be defined before including histogram_macros.h from this file.
-#define NET_DISK_CACHE_BACKEND_IMPL_CC_
 #include "net/disk_cache/histogram_macros.h"
 
+// Provide a BackendImpl object to macros from histogram_macros.h.
+#define CACHE_UMA_BACKEND_IMPL_OBJ this
+
 using base::Time;
 using base::TimeDelta;
 using base::TimeTicks;
diff --git a/net/disk_cache/backend_unittest.cc b/net/disk_cache/backend_unittest.cc
index 14ffbf0..8119f85 100644
--- a/net/disk_cache/backend_unittest.cc
+++ b/net/disk_cache/backend_unittest.cc
@@ -35,6 +35,9 @@
 #include "base/win/scoped_handle.h"
 #endif
 
+// Provide a BackendImpl object to macros from histogram_macros.h.
+#define CACHE_UMA_BACKEND_IMPL_OBJ backend_
+
 using base::Time;
 
 namespace {
diff --git a/net/disk_cache/entry_impl.cc b/net/disk_cache/entry_impl.cc
index 4b6e4cf..d6796d7 100644
--- a/net/disk_cache/entry_impl.cc
+++ b/net/disk_cache/entry_impl.cc
@@ -18,6 +18,9 @@
 #include "net/disk_cache/net_log_parameters.h"
 #include "net/disk_cache/sparse_control.h"
 
+// Provide a BackendImpl object to macros from histogram_macros.h.
+#define CACHE_UMA_BACKEND_IMPL_OBJ backend_
+
 using base::Time;
 using base::TimeDelta;
 using base::TimeTicks;
diff --git a/net/disk_cache/eviction.cc b/net/disk_cache/eviction.cc
index 47b5255..3e2c779 100644
--- a/net/disk_cache/eviction.cc
+++ b/net/disk_cache/eviction.cc
@@ -41,6 +41,9 @@
 #include "net/disk_cache/histogram_macros.h"
 #include "net/disk_cache/trace.h"
 
+// Provide a BackendImpl object to macros from histogram_macros.h.
+#define CACHE_UMA_BACKEND_IMPL_OBJ backend_
+
 using base::Time;
 using base::TimeTicks;
 
diff --git a/net/disk_cache/histogram_macros.h b/net/disk_cache/histogram_macros.h
index 651bce9..6af9ca1 100644
--- a/net/disk_cache/histogram_macros.h
+++ b/net/disk_cache/histogram_macros.h
@@ -84,12 +84,6 @@
 #define CACHE_HISTOGRAM_CACHE_ERROR(name, sample) \
     CACHE_HISTOGRAM_ENUMERATION(name, sample, 50)
 
-#ifdef NET_DISK_CACHE_BACKEND_IMPL_CC_
-#define BACKEND_OBJ this
-#else
-#define BACKEND_OBJ backend_
-#endif
-
 // Generates a UMA histogram of the given type, generating the proper name for
 // it (asking backend_->HistogramName), and adding the provided sample.
 // For example, to generate a regualar UMA_HISTOGRAM_COUNTS, this macro would
@@ -101,8 +95,9 @@
 //  UMA_HISTOGRAM_COUNTS("DiskCache.2.MyExperiment_530", 55);
 //
 #define CACHE_UMA(type, name, experiment, sample) {\
-    const std::string my_name = BACKEND_OBJ->HistogramName(name, experiment);\
-    switch (BACKEND_OBJ->cache_type()) {\
+    const std::string my_name =\
+        CACHE_UMA_BACKEND_IMPL_OBJ->HistogramName(name, experiment);\
+    switch (CACHE_UMA_BACKEND_IMPL_OBJ->cache_type()) {\
       case net::DISK_CACHE:\
         CACHE_HISTOGRAM_##type(my_name.data(), sample);\
         break;\
diff --git a/net/disk_cache/in_flight_backend_io.cc b/net/disk_cache/in_flight_backend_io.cc
index 3ed9e4d..394cc85 100644
--- a/net/disk_cache/in_flight_backend_io.cc
+++ b/net/disk_cache/in_flight_backend_io.cc
@@ -13,6 +13,9 @@
 #include "net/disk_cache/entry_impl.h"
 #include "net/disk_cache/histogram_macros.h"
 
+// Provide a BackendImpl object to macros from histogram_macros.h.
+#define CACHE_UMA_BACKEND_IMPL_OBJ backend_
+
 namespace disk_cache {
 
 BackendIO::BackendIO(InFlightIO* controller, BackendImpl* backend,
diff --git a/net/disk_cache/rankings.cc b/net/disk_cache/rankings.cc
index ff9913e..3ddbcf8 100644
--- a/net/disk_cache/rankings.cc
+++ b/net/disk_cache/rankings.cc
@@ -12,6 +12,9 @@
 #include "net/disk_cache/histogram_macros.h"
 #include "net/disk_cache/stress_support.h"
 
+// Provide a BackendImpl object to macros from histogram_macros.h.
+#define CACHE_UMA_BACKEND_IMPL_OBJ backend_
+
 using base::Time;
 using base::TimeTicks;
 
diff --git a/net/disk_cache/v3/backend_impl_v3.cc b/net/disk_cache/v3/backend_impl_v3.cc
index 7c85584..67dc861 100644
--- a/net/disk_cache/v3/backend_impl_v3.cc
+++ b/net/disk_cache/v3/backend_impl_v3.cc
@@ -28,11 +28,11 @@
 #include "net/disk_cache/storage_block-inl.h"
 #include "net/disk_cache/v3/disk_format_v3.h"
 #include "net/disk_cache/v3/entry_impl_v3.h"
+#include "net/disk_cache/v3/histogram_macros.h"
 #include "net/disk_cache/v3/index_table.h"
 
-// This has to be defined before including histogram_macros.h from this file.
-#define NET_DISK_CACHE_BACKEND_IMPL_CC_
-#include "net/disk_cache/v3/histogram_macros.h"
+// Provide a BackendImpl object to macros from histogram_macros.h.
+#define CACHE_UMA_BACKEND_IMPL_OBJ this
 
 using base::Time;
 using base::TimeDelta;
diff --git a/net/disk_cache/v3/backend_worker.cc b/net/disk_cache/v3/backend_worker.cc
index be12a96..a4acefb 100644
--- a/net/disk_cache/v3/backend_worker.cc
+++ b/net/disk_cache/v3/backend_worker.cc
@@ -26,11 +26,11 @@
 #include "net/disk_cache/errors.h"
 #include "net/disk_cache/experiments.h"
 #include "net/disk_cache/file.h"
-
-// This has to be defined before including histogram_macros.h from this file.
-#define NET_DISK_CACHE_BACKEND_IMPL_CC_
 #include "net/disk_cache/histogram_macros.h"
 
+// Provide a BackendImpl object to macros from histogram_macros.h.
+#define CACHE_UMA_BACKEND_IMPL_OBJ this
+
 using base::Time;
 using base::TimeDelta;
 using base::TimeTicks;
diff --git a/net/disk_cache/v3/entry_impl_v3.cc b/net/disk_cache/v3/entry_impl_v3.cc
index d748ed2..432a6a7 100644
--- a/net/disk_cache/v3/entry_impl_v3.cc
+++ b/net/disk_cache/v3/entry_impl_v3.cc
@@ -18,6 +18,9 @@
 #include "net/disk_cache/v3/histogram_macros.h"
 // #include "net/disk_cache/v3/sparse_control_v3.h"
 
+// Provide a BackendImpl object to macros from histogram_macros.h.
+#define CACHE_UMA_BACKEND_IMPL_OBJ backend_
+
 using base::Time;
 using base::TimeDelta;
 using base::TimeTicks;
diff --git a/net/disk_cache/v3/eviction_v3.cc b/net/disk_cache/v3/eviction_v3.cc
index 64b4c29..fc0d37a 100644
--- a/net/disk_cache/v3/eviction_v3.cc
+++ b/net/disk_cache/v3/eviction_v3.cc
@@ -40,6 +40,9 @@
 #include "net/disk_cache/v3/entry_impl_v3.h"
 #include "net/disk_cache/v3/histogram_macros.h"
 
+// Define CACHE_UMA_BACKEND_IMPL_OBJ to be a disk_cache::BackendImpl* in order
+// to use the CACHE_UMA histogram macro.
+#define CACHE_UMA_BACKEND_IMPL_OBJ backend_
 
 using base::Time;
 using base::TimeTicks;
diff --git a/net/disk_cache/v3/histogram_macros.h b/net/disk_cache/v3/histogram_macros.h
index 4f37970..50d4d75 100644
--- a/net/disk_cache/v3/histogram_macros.h
+++ b/net/disk_cache/v3/histogram_macros.h
@@ -84,12 +84,6 @@
 #define CACHE_HISTOGRAM_CACHE_ERROR(name, sample) \
     CACHE_HISTOGRAM_ENUMERATION(name, sample, 50)
 
-#ifdef NET_DISK_CACHE_BACKEND_IMPL_CC_
-#define BACKEND_OBJ this
-#else
-#define BACKEND_OBJ backend_
-#endif
-
 // Generates a UMA histogram of the given type, generating the proper name for
 // it (asking backend_->HistogramName), and adding the provided sample.
 // For example, to generate a regualar UMA_HISTOGRAM_COUNTS, this macro would
@@ -99,8 +93,9 @@
 //  UMA_HISTOGRAM_COUNTS("DiskCache3.MyName_AppCache", 20);
 //
 #define CACHE_UMA(type, name, sample) {\
-    const std::string my_name = BACKEND_OBJ->HistogramName(name);\
-    switch (BACKEND_OBJ->cache_type()) {\
+    const std::string my_name =\
+        CACHE_UMA_BACKEND_IMPL_OBJ->HistogramName(name);\
+    switch (CACHE_UMA_BACKEND_IMPL_OBJ->cache_type()) {\
       case net::DISK_CACHE:\
         CACHE_HISTOGRAM_##type(my_name.data(), sample);\
         break;\
diff --git a/net/net.gyp b/net/net.gyp
index 308c98d..348c134 100644
--- a/net/net.gyp
+++ b/net/net.gyp
@@ -457,6 +457,7 @@
         'disk_cache/v3/entry_impl_v3.h',
         'disk_cache/v3/eviction_v3.cc',
         'disk_cache/v3/eviction_v3.h',
+        'disk_cache/v3/histogram_macros.h',
         'disk_cache/v3/index_table.cc',
         'disk_cache/v3/index_table.h',
         'dns/address_sorter.h',