Namespace Log.h/cpp in dawn::

The LogMessage::LogMessage constructor was redefining a symbol that
exists in re2 inside of Chromium. So we namespace Log inside dawn:: to
avoid the conflict.

BUG=dawn:302

Change-Id: Ida349208e2c6fe9ac032e1bd8cd442dff0b3f6bc
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/14320
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>

src/common/Log.h

@@ -45,46 +45,51 @@
 
 #include <sstream>
 
-// Log levels mostly used to signal intent where the log message is produced and used to route the
-// message to the correct output.
-enum class LogSeverity {
-    Debug,
-    Info,
-    Warning,
-    Error,
-};
+namespace dawn {
 
-// Essentially an ostringstream that will print itself in its destructor.
-class LogMessage {
-  public:
-    LogMessage(LogSeverity severity);
-    ~LogMessage();
+    // Log levels mostly used to signal intent where the log message is produced and used to route
+    // the message to the correct output.
+    enum class LogSeverity {
+        Debug,
+        Info,
+        Warning,
+        Error,
+    };
 
-    LogMessage(LogMessage&& other) = default;
-    LogMessage& operator=(LogMessage&& other) = default;
+    // Essentially an ostringstream that will print itself in its destructor.
+    class LogMessage {
+      public:
+        LogMessage(LogSeverity severity);
+        ~LogMessage();
 
-    template <typename T>
-    LogMessage& operator<<(T&& value) {
-        mStream << value;
-        return *this;
-    }
+        LogMessage(LogMessage&& other) = default;
+        LogMessage& operator=(LogMessage&& other) = default;
 
-  private:
-    LogMessage(const LogMessage& other) = delete;
-    LogMessage& operator=(const LogMessage& other) = delete;
+        template <typename T>
+        LogMessage& operator<<(T&& value) {
+            mStream << value;
+            return *this;
+        }
 
-    LogSeverity mSeverity;
-    std::ostringstream mStream;
-};
+      private:
+        LogMessage(const LogMessage& other) = delete;
+        LogMessage& operator=(const LogMessage& other) = delete;
 
-// Short-hands to create a LogMessage with the respective severity.
-LogMessage DebugLog();
-LogMessage InfoLog();
-LogMessage WarningLog();
-LogMessage ErrorLog();
+        LogSeverity mSeverity;
+        std::ostringstream mStream;
+    };
 
-// DAWN_DEBUG is a helper macro that creates a DebugLog and outputs file/line/function information
-LogMessage DebugLog(const char* file, const char* function, int line);
-#define DAWN_DEBUG() DebugLog(__FILE__, __func__, __LINE__)
+    // Short-hands to create a LogMessage with the respective severity.
+    LogMessage DebugLog();
+    LogMessage InfoLog();
+    LogMessage WarningLog();
+    LogMessage ErrorLog();
+
+    // DAWN_DEBUG is a helper macro that creates a DebugLog and outputs file/line/function
+    // information
+    LogMessage DebugLog(const char* file, const char* function, int line);
+#define DAWN_DEBUG() ::dawn::DebugLog(__FILE__, __func__, __LINE__)
+
+}  // namespace dawn
 
 #endif  // COMMON_LOG_H_